most of the cheap ebay kits are usually crappy fiberglass that cracks easily and won't fit very well. a few of my friends have had cheap bumpers like that and they tend to break/crack extremely easily and take quite a bit of modification to fit cleanly.

2 of the cheaper companies i've know of that are supposed to be decent for the price are BMagic and version select, you might wanna check those out (they seem to be made fairly well and fit alright for the price).