A number of unscrupulous sellers list their Games Workshop items as RARE or NO LONGER AVAILABLE, or even both. Before you rush in with a bid for that "must have" miniature, check out the Games Workshop Online site and look at the "Classics and Collectors" miniatures that are found at the top of each page of each different category of army in the games Workshop range. You will often find that the figure described as RARE or NO LONGER AVAILABLE is neither rare or unavailable but ready to be ordered online from Games Workshop!!
There are many honest and brilliant sellers of Games Workshop figures out there, but do not be caught out by the few who are not. Check the sellers feedback and see what other buyers have said.
It's already been said but needs to be repeated - Epic scale miniatures have been sold by less than honest sellers implying they are fullscale 40K miniatures, don't get suckered into buying one thinking it was full size like I was!
And as a final point, ALWAYS ALWAYS check the postage costs! That figure you think is really cheap may not turn out to be as cheap as you thought if you then have to pay over the top for postage.