I bought a second-hand ipad 2 from a repuatable pawn shop. All pawn shops have to check serial numbers against police reports for stoeln merchandise, and it comes up clean also with apple. So why is the imei blacklisted?

1. If the device were not reported stolen to either the police or to apple, it wouldn't show up on those lists. That doesn't mean it wasn't lost or stolen, just that it wasn't reported through those channels.
2. Locate the model number of the iPad on the back of the device, and check it against this: http://support.apple.com/kb/HT5452. If you are getting an IMEI block, I'm betting it is in fact a 3G model.
3. Consider returning it. If the IMEI is blocked, prior ownership of the device is not as free and clear as the pawn shop owner would have you believe (or believes himself).
4. A tip: purchasing computer equipment through a pawnshop is rather risky, especially mobile devices. It may seem like a deal, but odds are pretty good you are buying a package of issues. Stick to reputable dealers.

Like James said, there is a reason it sells at a discount at a pawn shop. For me at least, the relatively small savings isn't worth the potential risk and disappointment of getting a stolen device. You can get refurbished devices directly from Apple at a modest discount

😎

Glad you got it sorted out.

This might be worth taking a look at: http://store.apple.com/us/browse/home/specialdeals