Fencing is illegal. If you have my laptop, you have to give it back to me, or you are yourself a criminal.
If, on the other hand, the scenario was real, why would I reimburse your kid's foray into stolen goods? He got the $50 in the first place, he spend them on crime, he should "do the time".
Amazingly, I think this is actually almost feasible, at least with regard to the "fencing" of the stolen product. If you only attempted to swindle $50 out of someone with this, it would very likely have a very high success rate.
Unfortunately, the economics don't work out w/respect to the risks/overhead involved in the theft of said product.
2. Call victim and claim your kid bought stolen laptop for $50 and 'fessed up.
3. Claim you'd give it back for said $50
4. Profit $50.
4a. Appear innocent.