QuikTrip sells them for a dollar. Its pretty fast. You go to QT with the cash + $1 and tell them how much you want to make out the money order for. Then you fill out the money order exactly like a check.

However, the money order will ask you for either your address, or the other person's address, i believe its yours. Then you tear it off, keep the stub, fill in the stuff with your personal information and for your own record, in case the money order gets lost, and just mail it off like a regular check