I totally believe you. Seriously, I'm not being sarcastic. I had a similar problem with my first iPhone 4 (cracked out of nowhere). For this reason, I'm a true believer that Apple products are not exempt from manufacturing defects, like most people think. Most people immediately put blame on the customer for anything physically breaking, which I wholeheartedly disagree with.
Rant aside, I think you're pretty much screwed in terms of warranty repair. If you had just left it alone and not ripped apart the glass, you would have been fine.
So your only option, whether you do it yourself or get someone else to do it, is to replace the glass. Apple does not sell replacement glass pieces, so you'd have to buy a replica. They're usually ~$50 and come with adhesive strips already. Remove all the glass, all the glue, attach the webcam bracket to the new piece of glass, make sure your webcam cable is plugged in, then just expose the adhesive strips on the replacement glass and firmly press it into place. The key is to make sure ALL off the glass and ALL of the glue is *completely* gone; the surface must be super clean.
If you still think you'd rather sell it, PM me the specs of the machine and a price. I would buy it, fix it, sell it, and hopefully have enough money to buy a textbook because I'm broke as hell.