[Moogs]

You're dealing with some crooked MOFOs Wickes.

Ask yourself why someone would willingly pay you 10x as much as your asking price, and have someone else pay you, etc etc. When this kind of money is involved, unsavory types are usually involved, which means if you set them off you could be in some danger without even knowing where to look for trouble.

I'm not a fan of Paypal but for this kind of thing it would've been preferable to this whole shady third party check thing.

If you're going to be selling a lot of stuff / dealing with strangers and their money, I might consider getting a PO Box, and having all payments be money-order only... sent to that box. Don't give people your address. That's the real problem here now, because if these people turn out to be real scumbags, they know where you live. Phone number is one thing, but never give your address to complete strangers like that.

As for the check, I'd carefully void it with a date and your initials right underneath, and take it to the equivalent of the FBI in your area (someone with more resources and training at their disposal than garden variety cops).

Tell them that you were expecting a check for MUCH less than what they were claiming (i.e. you figured they were lying about the amounts), and that when this thing arrived, you knew immediately something was wrong and so went to the authorities. Don't start playing games with these people (sending the envelope around, telling them not to contact you, etc.).

They have your contact information so there's nothing you can do about that except ignore them. Screen your calls with voicemail, bounce their email to the trash, etc. Don't say another word to these people until you talk to someone in a position of authority. For all they know, you're not responding because you're sick. As long as the check doesn't get cashed, hopefully they won't think you're trying to scam them or whatever.