i think if people start mailing them loads of frames, they will realise that they are under priced and bump it up to whatever other shops charge. i'm guessing the only reason its so cheap is because the rarely (if ever) get this sort of request.

edit: i'm not saying you shouldn't try, it might be worth a phone call. they could need the business. i'm just saying don't expect it to stay that cheap if demand skyrockets.