Not that good of a deal now. At $20 plus bucks (and the auction isn't over yet) and $3.99 shipping, that's close to what they sell for.
There are deals to be had on eBay tho, I bought 2 incase sliders for 3G iPhones for under $10 including shipping. Not trying to rub your nose in it by any means but you just need to be patient and do not bid till about the last 10-12 seconds of the auction. I also waited over a month to get a deal.