Just came across the thread, not sure if its too old but I just thought I'd register and give my 2 cents.
I'm very happy with my bumper purchase from ebay seller iLidz_Store priced at $15.99 USD, primarily because they carry their stock the U.S. (fast shipping, though I'm located in the same state so I got overnight delivery

) and their customer service is quick, polite, and fluent in English. Though more expensive than the typical Hong Kong seller, their service is superb and shipping was prompt. Pictures in the description were cool too haha, looks much more reliable.
I've attached some pictures below to share one of the few bumpers I've purchased from them. Sorry, haven't had time to open and try the rest, let alone photograph them

.
My only complaint, they shipped in a smaller sized bubble envelope. I had hoped to see something much larger in the mail to feed my excitement

haha.
Check out their listing (you can click the pictures of the different colored bumpers to view their other listings for their other bumpers as well):
http://cgi.ebay.com/OEM-APPLE-IPHONE-4-4G-BUMPER-TPU-FRAME-CASE-NEW-BLACK-/200547723552?pt=PDA_Accessories&hash=item2eb1936920
As some of you have had issues about the shiny buttons with the fake ebay bumpers, this one has matte buttons that are very tactile.
Hope this could help!
**on a side note, I should've had my typophone lock screen on..would've looked great with the bumper!