Clever money laundering?

So I posted my old Audi A4 rubber floor mats forsale on Craigslist - Seattle. I then get this email in an offer to buy them. But the dudes in South Africa. And he wants to pay me by having someone who "owes him money" send me a funds for $2000, have me deduct the cost of my floor mats ($65 + shipping), and then send the balance back to the South African guy via Money Gram or Western Union.

So if the guy who owes the South African money sends me certified funds, then those funds are guarenteed? The obvious scam is to "sell" someone money that isn't real (Thanks Matchstick Men). Meaning I'd be shipping my floor mats and ~$1900 to this guy for a bad $2000 check. But if this dudes money is real, is this just some way to launder money?