Innocence of youth

My nephew has just started reading History at Manchester University. He called me yesterday saying, "I've had a disaster. Please call me back immediately!" It transpired that on his way back from his lectures yesterday, he was approached by some men who had a van load of speakers. My nephew's really into music so his attention was caught. They spun him a tale which boiled down to this business deal: if he bought one of their speakers for £350, he would be able to sell it on e-Bay for $3000. Robert says he asked them loads of questions and was convinced that they were genuine. (Then, why weren't they simply doing this deal themselves?) Anyway, he gave them £350, took the speaker back to his Hall of Residence where it could barely fit into his room, looked at the internet site about the speaker which appeared fine on the face of it but which on further inspection proved, surprise, surprise, to be a complete sham. He then discovered many comments from other people who'd been conned by this scam. He didn't take the registration number of the van. He went to the police who said there was nothing they could do about it. I'm still debating whether he's stupid or simply naive.