People keep backing out of sales that Ive won!!!

[gihib_2014]

Four times in a row I have had items that Ive won or very close to winning removed from sale and not sent to me. One guy called me a cheap skate for not bidding hi enough so he wouldnt sell the item to me even though I had won te auction. Is this right. Can people just retract an item? Another edited his post to say that payment should be made within 24 hours or no sale would take place and then removed the item with informing me of the change. Again is this correct and if not how do we mark the sellers as rouges?