The other two times you listed it, you had an auction with a buy it now option

I can't see a completed sale for the price you mention, only one for $75.00 plus postage 

As mentioned, if someone bids, the 'buy it now' vanishes and it becomes an auction only, the highest bid (no matter how many bids there are) wins and you need to honour that sale

There are no 'reserves' so if you want a certain price, don't offer an auction, or only start an auction at a bid you are happy with

Have you signed up for Managed Payments and been given the go ahead to start selling already? 

And are you aware of the hold on funds as you a new seller?