Been there, done it. I 'bought' a link from ebay two weeks ago for £2.50. As Mike says, it directs you to a site where, for £25, you go at the foot of a list. When you are eventually 'pushed' to the top of the list, you get your goodies.
Declined to do it myself, but when I tried to resell the link on (seeing an 'opportunity') ebay kicked it off, with a friendly warning. I've noticed the guy I bought the link off is now 'no longer a registered user'.