They are not asking for an upfront fee, only 5% commission but thats not upfront
If you've had a chance to read other posts on these boards, you'll see that many others have come on here mentioning the exact same type of phone call they received.
Unfortunately, some found TUG too late and fell for the scam. It's the same thing each time. The scammer phones the owner saying he found a buyer who has just put down a 20% non-refundable deposit and is committed to going ahead with the buy (for an unreasonably high amount like $25000, or so).
Then, while you're drooling and dreaming of what you're going to do with this life-altering amount of money and thinking to yourself "Great! Great! What do I have to do to complete the process?", the scammer, magically reading your mind, says, "We just need you to send us $948 for [insert bogus fee here such as prepaid closing costs, Mexican back taxes, retainer fee, lien search, etc.]. But once the papers are done, this fee will be refunded to you."
Can you guess what happens once the owner sends that money (usually via wire transfer so that there is no paper trail to track him down once he has your money)? I'll give you two choices:
A) The transaction is completed expediently. The owner gets a cashier's cheque for $24698 ($25000 less the 5% commission plus the $948 fee refunded. The owner is on Cloud 9 with all that money. Or
B) Then owner never hears back from the scammer. He still owns his onerous timeshare. All phone calls to the scammer are now to a disconnected number. All e-mails are to a discontinued e-mail address.