It is July 2015 and the Juventus manager, Massimiliano Allegri, is talking excitedly about the club’s latest signing. Juve may have won the league title by a whopping 17 points the previous season but Allegri wants his squad to evolve and to become even better.

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“He seems like a little kid on the first day of school,” Allegri says of the new arrival. “He’s in great shape because he’s been training over the summer and he’s really enthusiastic – it’s contagious. He’s a huge, strong and charismatic signing for us. He’s shown great professionalism. You know, in terms of experience we’ve got all we need. I’m really pleased with this project.”

Who was the player the manager was so delighted to have landed? A certain Sami Khedira, who had made only 11 league appearances in his last season at Real Madrid, scoring no goals. His injury record was poor and there were even suggestions that, at 28, he had peaked. Juve and Allegri saw it differently. They saw a World Cup winner with huge potential and a desire to prove everyone wrong. The best thing about it? He arrived on a free transfer.

And the German midfielder is not the only player to have cost Juve nothing. Last summer Dani Alves also joined on a free, Barcelona having decided that the Brazilian was no longer of any use to them. He, too, has been an excellent acquisition.

Alves and Khedira are two big reasons why Juve have reached the Champions League final against Real Madrid on Saturday and while no one is pretending that they are a poor club punching above their weight – they are, in fact, ridiculously wealthy – they have showed a lot of clubs around Europe how to recruit in recent years.

They have kept their reliable veterans at the back – Gianluigi Buffon, Giorgio Chiellini, Leonardo Bonucci and Andrea Barzagli – brought in cheap but invaluable experience in Khedira and Alves and added star dust, goals and creativity in expensive signings such as Gonzalo Higuaín, who cost a mouth‑watering £75.3m from Napoli last summer, and Miralem Pjanic and Marko Pjaca for a total of £48.5m.

Perhaps the most impressive thing about Juve’s recent transfer policy is that they ended up with a net spend of only £15.67m last summer after selling Paul Pogba (who arrived on a free), Álvaro Morata and Roberto Pereyra among others.

Here are five Juventus players who – for very different price tags – have contributed towards making Allegri’s squad one of the best in European football.

Dani Alves

Arrived on a free transfer in 2016 after leaving Barcelona

Facebook Twitter Pinterest Dani Alves had a hand in all four of Juventus’ goals in the two-legged semi-final against Monaco, scoring once and providing three assists. Photograph: NurPhoto via Getty Images

The Brazilian has confounded his critics – once again – by overcoming a broken leg in November to play a crucial part in getting Juventus to the Champions League final. In the semi-finals against Monaco, the 34-year-old had a hand in all four Juventus goals in the 4-1 aggregate win, scoring one and providing three assists. But it is not only on the pitch that Alves has had an impact. He is an infectious character who has brought a bit of joy and sparkle to a “serious” dressing room. “I’m a big believer in energy, and I feel that what you do on the pitch reflects who you are off it,” he said last month. “That’s one problem I’ve had. In Italy team-mates can be a bit serious and not very expressive. I’m the complete opposite – I’m happy, fun to be around, and I like to get an atmosphere going.” Bonucci calls him “an alien” who has reached “surreal levels” this season.

Alex Sandro

Signed from Porto for £22m in 2015

Facebook Twitter Pinterest Alex Sandro has become one of the most sought-after left-backs in the world, with Chelsea’s Antonio Conte among his many admirers. Photograph: Miguel Medina/AFP/Getty Images

Now, paying £22m for a full-back is pretty extravagant but that fee still seems shrewd considering the progress Alex Sandro has made since joining from Porto. The signing was hardly a gamble: the Brazilian had been in Europe for four seasons and performed consistently in the Primeira Liga, Champions League and Europa League since breaking into the first team. However, there were still doubts about whether he could cope in Serie A. Successive Brazil managers have overlooked him and he has only six caps.

The answer has been emphatic. The 26-year-old has, at Juve, become one of the most sought-after left-backs in the world, with Antonio Conte desperate to bring him to Chelsea. He is a complete footballer with accurate crossing, whose overall game is rivalled by few. “He’s a technical, modern full-back: someone who can defend and attack,” says the former Brazil left-back Roberto Carlos. “In Brazil he gets compared to me and to tell the truth I see myself in him a bit …”

Sami Khedira

Arrived on a free transfer in 2015 after leaving Real Madrid

Facebook Twitter Pinterest Sami Khedira, right, keeps the ball from Barcelona’s Lionel Messi and Sergio Busquets during the Champions League quarter-final. Photograph: Marco Bertorello/AFP/Getty Images

Juventus fans feared the worst when the imposing German was carried off with a serious-looking injury in one of his first games for the club, a pre-season friendly against Marseille. The club revealed that he had suffered a tear in his right thigh and he did not make his competitive debut for Juve until the end of September. Since then, though, he has given the Serie A champions everything they wanted from him: power, crisp passing, discipline and a box-to-box presence that is so important in the modern game. This week, as he hopes to overcome an injury to face his former club, he told Kicker: “In Madrid I was appreciated by my managers but not by the public. When I played 10 good games then that was taken for granted. When the 11th game didn’t go that well I was immediately criticised and it was questioned whether I was good enough for the club.”

Mario Mandzukic

Signed from Atlético Madrid for £17.85m in 2015

Facebook Twitter Pinterest Juventus’ Mario Mandzukic has been transformed from a striker to an effective, hard-working wide player who occasionally also plays at wing-back. Photograph: Filippo Monteforte/AFP/Getty Images

Perhaps the most remarkable aspect of the Croat’s success at Juve is the fact that up until he arrived in Turin he had played the majority of his career as a striker. Allegri, however, has turned this former goal machine into a hard-working wide player, at times playing as a left wing-back. The transformation has been astonishing and a player who turned 31 last month has fully repaid a manager who signed him after a one-season stint at Atlético. As Buffon said when asked what it would take Juventus to win the Champions League: “We need to take Mario as an example: He’s like a huge aggressive gorilla, the type that never goes down, running around wildly with flies around his nose.” Quite a compliment …

Leonardo Bonucci

Signed from Bari for £13.5m in 2010

Facebook Twitter Pinterest Leonardo Bonucci, right, has been a mainstay for both Juventus and Italy after being signed from Bari in 2010. Photograph: Antonio Calanni/AP

Internazionale must still be cursing their decision to let him go eight years ago, having sent him out on loan twice before selling him to Bari. One season and an extraordinary central defensive partnership with Andrea Ranocchia later, he joined Juventus. Bonucci, who turned 30 last month, did not have the best of starts in Turin under Luigi Delneri as, in his own words, he “didn’t turn up for pre-season in the best shape after my wedding and honeymoon” but after Antonio Conte took over in 2011 it did not take him long to whip the defender into shape and Bonucci has been a mainstay for club and country for several years now. He considered quitting football last summer after his son, Matteo, fell ill and the player fell out with Allegri during a game against Palermo, with the pair trading insults before continuing the argument in the dressing room. Bonucci was subsequently dropped for a game against Porto. He later apologised, adding: “The night in Porto was tough, I won’t deny it, but it helped the squad and, foremost, me. We win together and we lose together.”