Money pack is safe its best to use it if you live in the USA that the only way I know, also if he has money pack he can easily buy of you using PA or something else if you dont know how to use money pack read up on it as Roary posted above. I know its easy as using a CC and its safe to use. Once you get the MP just use the cash on it therefore he cant charge it back even if it allows charge back. Another thing you might want to look into is if its like a gift card remember you and the user have the card # and security code so its best to use it whenever you get it, or as time goes past the user might use it. Just a heads up.
Remember if there's a will there is a way. Dont give things like this benefit or the doubt.