The reality of Melbourne’s cooling property market has cast doubt over whether all five apartments renovated on The Block will sell under the hammer this weekend.

With auction clearance rates at their lowest level in years, property experts say it is increasingly likely that at least one of the apartments in the former Gatwick Hotel will pass in.

More than two million people are expected to tune in to watch the finale of Channel Nine’s popular renovation show on Sunday night. But television crews aside, the outcome depends entirely on how much a handful of wealthy buyers are prepared to cough up.

It is well established that the nation’s property market is coming off the boil. And, according to Domain Group data, house prices slipped 3.9 per cent in Melbourne in the three months to September.

In recent weeks, Melbourne’s clearance rate has fallen below 50 per cent. That means if just three apartments sell under the hammer, The Block will have bucked the trend.

In the three months to September, St Kilda recorded a 47 per cent clearance rate while its neighbour St Kilda West achieved 53 per cent.

Observers also point to a change in market sentiment; buyers are more cautious at auction and hope to gain the upper hand in negotiations if a property passes in.

Set against this backdrop, could this season’s contestants achieve a 100 per cent clearance rate?

“Stranger things have happened,” said Greville Pabst, buyers advocate and regular Block bidder. “But you’d think on the balance of it, it’s unlikely.”

“Buyers are thin on the ground, particularly at this level of value, at $2.5 million.”

It’s also important to note that there are 1399 other properties listed to go to auction this weekend in Melbourne, a competitive environment for any vendor to be in.

The Agency’s Michael Paproth, the agent handling the sale of Bianca and Carla’s penthouse, said while The Block was not immune to softening property conditions, the Gatwick was a unique offering.

“The downturn in the market doesn’t discriminate – it is affecting all properties,” Mr Paproth said. “But this has a special interest, it’s an iconic building and that’s what will save the day.

“Whether the market is up or down, you can’t repeat this.”

Up for grabs are two penthouse apartments and three apartments in the original Gatwick building. Advertised price guides range from $2.2 million to $2.8 million. With floor space over 250 square metres, the three-bedroom properties are larger than many freestanding houses.

But it is the single car space that comes with each apartment that has been a deal-breaker for some. Domain understands several potential buyers have dropped out of the race, citing the lack of a second car space.

The successful sale of each apartment could hinge on the reserve prices, which Channel Nine is yet to reveal.

“It will depend on how high the reserves are set as to whether all five apartments sell at auction,” said Frank Valentic, director of Advantage Property Consulting.

“As always, I think the order of auctions will play a big part, as usually the most successful Block series have been when the most popular properties have gone first, followed by the least popular properties.”

Related: View the five Gatwick apartments for sale