Well, if you feel it's stolen, and you contact the police, not only will you be out $150 bucks, but the device as well as they will confiscate it. Not to mention several hours at the police station answering questions, filling paperwork. Also, you'll be added to the "watch" list for buying and receiving stolen property. Probably be added to the "additional security" list at airports and train stations. With the way things are nowdays, who knows what else will happen.
After all, you paid $150 for a $300 phone. Well under the retail value. So they will say you should have known it was stolen.
Probably, some idiot didn't want to pay his/her bill, and reported it stolen to get out of the contract, so they could get a newer phone.
Bypass the activation, unlock it, and hope for the best. Cops "should" have better things to do, than to waste resources tracking stolen phones.
Stolen donut trucks, are different a story....