Woooo, LH - can you also offer to help Enron out of their jam ?!
I have also received several varieties of this and at least two in hard-copy to my business name, over the last few years.
This is a "classic" scam, and does seem to be usually "based" and no, I don't know why, but I speculate that country's laws may be more liberal regarding fraud via mail.
I even crewed on a very-low-budget direct-to-video feature with a script that centered around such a scam. The punch line: It was written and directed by two Nigerians who are professors at University of Houston !! I thought the script was too long and the edited version I saw was also - like they couldn't stand to trim anything at all from it.
BORING to TEARS - but I heard that they marketed it successfully IN Nigeria, that it was popular and that the pacing was culturally typical of what the target audience expected and enjoyed.
The bad guys, both American and Nigerian, got what they deserved and yes, I did get paid on schedule and per agreement. I doubt you would find this in any mainstream video store, but you could search for it under the title "Stalk Exchange" if you have serious need of a remedy for insomnia !!