A friend of a friend used to do this for people dealing with another product type. The US Customs finally got suss to what was going on and the person in question ended up with a sizeable fine for fraud. You're basically asking them to commit fraud so don't be surprised if you get a no.
The other way to do it - Fly out with a package (old PC) and fly back with a new one. You have outbound flight details showing you checked in extra baggage and what type it was. If done properly and sparingly you can fund a trip, an old acquaintance used to do this with high end mountain bikes and more than paid for his flights in savings.