My view on ebay armor is that you shouldn't buy from folks who are "armor vendors". Once and awhile you will find 501st members or other prop collectors (who know their stuff) who are selling quality items on ebay.
Looks like you found an FX. At this point, it is passable for 501st membership. BUt if you've been lurking around these forums I'm sure you've noticed that there are better alternatives to the FX armor.