Here I must agree. Generally, the mistake was setting only a week time limit for the auction. It's not normal to buy a house without even seeing it IRL and without having anough time to make a decision. It's OK only if you buy it a few times cheaper than the market price.
However, I think 'scam' is not the right word here. If one places a bet, the only thing he might lose is his time. Nobody is going to transfer BTC before the agreement is signed anyway.