purchasing hosting from e-bay is not unlike purchasing anything else there.
if you follow these basic suggestions, you should be ok.
1 don't buy from folks you can get no info on.
2 if it sounds too good to be true, it most likely is
3 never spend more than you can afford to completely lose
4 the seller IS out to make money
5 let the buyer beware
6 if it seems shady, it most likely is
7 whats the worst that could happen, because it might.
i've had many problems resoplving issues from e-bay sales gone bad, and they have TRIED to help, but in the long run, were rather lackluster. look at how much they have to police.
personally, i doubt i would EVER buy hosting from e-bay, or any other similar auction type site. much better to strike a good deal witha good host, then to maybe skin by witha good auction, then be stranded a ways down the line.
this is purely my opinion though, i in no way represent e-bay, and honestly buy and sell there rather often. but i ALWAYS follow those guidelines.
maybe i am a prude, but once bitten, twice shy.