If you do something like that, go into your paypal account and remove all of your checking accounts. If it is a scam and they take credit card money that's one thing .... but if they take your cash, it's gone (at least for awhile).
I believe that if they are serious and honest, they will just hit the paypal button and pay. Asking for weird stuff is not only unnecessary, but fishy.
I guess I'm old school, but if someone calls me on the phone and says "$100 check is in the mail, will you hold it for me?" it's done. If they can't get here for a few days because they are making a living, no problem. Just don't foozle me with electronic nonsense ... make a phone call.