I've heard of this particular scam against sellers on eBay and Craig's List, but I use neither for my art, only my website, so this one is pretty sophisticated, except for the English, as you will see.
The first email from "Michael" was: "i will like to know if Oasis and Left at the station is still available for sales." I did notice the awkward construction of the query, but figured it was just careless typing, so I replied that the work was available.
The second email convinced me that it's a scam: "Thanks for the message, I am very happy to know that the artwork is still available for sale. i must tell you i am very much interested in the immediate purchase.
I will like to let you know that your payment will be in form of a Check and i will wait till it clears in your bank before telling my shipper to come for the pick up.
This is because i will be traveling out of the country any moment from now for a business proposal..So get back to me with the information needed to send you the payment I:E :
Phone number (with area code)
so that i can proceed in the payment arrangement.
The way this works is you receive a check for an amount larger than the price and the "buyer" explains that it's a mistake, so after the check clears, just send the difference to him.
Your bank tells you the check has cleared, you assume you have more than you asked for safely in the bank, so you send the difference via Western Union or bank transfer, and then sometime later your bank tells you that the check is no good.
Please be careful; there are some very bad boys out there!