hmmm. the fact that there could be legitimate users of Moneygram did seem too good to be true.
Bog standard e-bay scam then – report non paying bidder and get relisted.
Also see 419eater.com for a laugh 🙂 (Hope it’s ok to post a link here).
Miscellaneous scams section forum has some good info about the scams that all eminate from Nigeria.