Money can’t buy you love, it was once said. Not true. Money also can buy you happiness, lots of cool stuff and, in the Raiders’ case, long-lost competitiveness and respect.

As long as they’re not shy about spending it.

NFL free agency starts Tuesday and the Raiders, in Year 4 of their rebuilding process, will have close to $70 million available under the salary cap. They should have their sights set on the biggest and meanest fish available: defensive tackle Ndamukong Suh.

Oakland has interest, sources said, but it’s going to take a lot more than interest.

Suh, whom the Lions declined to keep Monday at the cost of a $27 million franchise tag, is set to become the highest-paid defensive player in NFL history.

He’s in the prime of his career at 28, and has been a 6-foot-4, 305-pound force since Detroit drafted the Portland native with the No. 2 overall pick in 2010. He has 36 sacks in five seasons, snacks on interior linemen and running backs, and last year led the Lions to the playoffs.

It’s a no-brainer. Suh said his agent will pick his new team, so the Raiders must keep throwing money at them until the two gentlemen blink. Even if it gets up to a seven-year deal — the maximum allowed under the collective bargaining agreement — for $120 million or so (with $70 million guaranteed).

Oakland is 11-37 in three seasons under general manager Reggie McKenzie, who, depending on who you ask, has dug the Raiders out from salary-cap hell and/or taken some huge swings and misses with trades, draft picks and signings.

Oakland is $56.3 million under the salary cap with the release of safety Tyvon Branch becoming official Tuesday. That becomes a league-high $69.5 million with the expected departures of defensive end LaMarr Woodley, quarterback Matt Schaub and running back Maurice Jones-Drew. That can buy a lot of players.

Suh represents a chance to add an impact player of the highest order, as well as send a message to players around the league that Oakland is not simply a place where older players go to die.

It’s fun spending other people’s $120 million, so I wanted to make sure I was doing the right thing by earmarking the Raiders’ funds for Suh.

Former NFL agent and analyst Joel Corry agreed, and left off any sugar coating.

“They should give him a blank check,” Corry said. “They are going to have to overspend, anyway, on whoever they get, because of their losing culture, so why not do it on the best guy available?

“Overpay for an impact player in his prime.”

Suh certainly would help pass rushers Khalil Mack, Sio Moore and Justin Tuck, as quarterbacks no longer would be able to step forward to avoid the outside rush. The Raiders had only 22 sacks last year and were 22nd against the run.

Suh is durable and hasn’t missed a game to injury in his five years. He has missed two, though, to suspension, for stomping on a player in 2011. Teammates love his passion, but opponents call him a dirty player.

Tuck has a different word.

He’s “Raider-ish,” Tuck said during Super Bowl week. “And that’s one of the reasons why I know Raider Nation would applaud that move, beyond the fact that he’s an awesome football player. He kind of fits the mold of ... the toughness and the ferocious player that built the Oakland Raiders.”

McKenzie was trained in Green Bay, where he learned from Hall of Fame general manager Ron Wolf to build through the draft and avoid overpaying free agents. But there is a time to pick your spots, and Wolf credits the big free-agent signing of Reggie White in 1993 with helping turn around the franchise.

Suh is the Raiders’ White.

“Hopefully, it works out for us,” Tuck said, “and I get an opportunity to play with that guy, because it would be phenomenal for what we’re trying to build in Oakland.”

Vic Tafur is a San Francisco Chronicle staff writer. E-mail: vtafur@sfchronicle.com Twitter: @VicTafur