I just checked, postal service money orders cost 1.20 and western union money orders cost between 99 cents and 1.50. You can send maximum 1,000USD. That's for USA. Yes, you can send from Smiths grocery store.
So if you are in USA, you could send someone 10$ for his/her GCR using money order. I'm not the one though, I only have 0.4 GCR at the moment ;-)
Nice. Sounds convenient. Maybe something to keep in mind should someone have the same need that I do. :)
For now I seem to be good because the guy I traded today with seems to want to do this regularly.