Used Tractor Values

In our local paper, somebody put an advertisement for a tractor. The tractor sounds nice and at a good price. However, when I e-mailed the person, he said he wanted to use Yahoo! Finance for the transaction. And he is located somewhere across the country, many miles away.
Is this a real service? and how foolproof is it?
His statement was this:
“…I want to use Yahoo! Finance for this transaction. This service allows us to complete the transaction in a manner that is quick and safe for both of us. It acts like a third party between seller and buyer, to insure that the buyer receives the item and the seller receives the payment,…”
Thanks!

I Answered An Add For The Sale of A Tractor. When All Was Agreed to, And Payment Was To Be Sent Through Yahoo Finance.
I Received An email From what Seemed to Be Yahoo Finance, With Instructions To Send A Money gram To Their Agent. Could Not Get A Confirmation He Was An Agent of Yahoo, And Money gram would only Accept to Send to an Individual, Since They Did NOT give ME A 4 # cODE