0 . Accept that the money's gone. It could, as others have mentioned, been a lot more.
1 . Learn
Make sure your son (and you!) have learned the lesson (at least try to get something out of the $650). The world isn't always a nice place unfortunately. Don't wire money to strangers - use an escrow service or paypal or similar. As the saying goes: "Fool me once, shame on you. Fool me twice, shame on me".
2 . Report it to the authorities.
Does have the advantage of the domestic rather than foreign bank account used. The scammer might have closed it by now, but there should be some paper tail. I imagine the id required for opening a bank account in the US is as strict as it is most places these days. They may have used fake Id, but that's not your problem.
Assuming contact was made over the internet, bearing in mind IANAL (or American), this could be a crime of Wire Fraud, in which case I believe it's a case for the FBI rather than your local police. The phone calls your son is still receiving could also be construed as attempted extortion and if across state lines could also come under federal jurisdiction.
The FBI have a better chance of catching such a scammer, generally having more chance of knowing one end of a computer from the other compared to a local beat cop. If other victims have also contacted the authorities, it will probably be taken more seriously.
Give as much information as you can. Not just the bank account details, but all communication, exact time of phone calls, etc.
The cops may say there's nothing they can do as it's a civil matter (breach of contract) rather than a criminal one. In which case you have the (probably expensive) option of going the civil route as described by Harper above.
3 . Inform Others
Assuming initial contact with the scammer was made through a website or forum or similar. I imagine this must be a niche area for hand made toys. Post your experience to warn other potential victims. Inform the site owner - they may ban the scammers account where applicable.
4 . Stop the calls.
Block the number. If the number's being withheld, contact the provider - they should have a policy regarding harassment and be able to block it their end. If the calls keep coming, your son will need to change his number.
5 . Don't let it get to you
You may have warm cosy fantasies of removing the guys kneecaps with a 2x4. Don't however dwell on the b*stard for too long and let it get under your skin. You will have to let it go.