Intel lowered their prices with the release of the 18 core for 2000$. Before AMD became competitive again you had to pay 1700$ for only 10 cores or go for a 3000$ or 4000$ 18 core Xeon.

EDIT - of course there are also Xeons between 10 and 18 cores, but it should show that you had to pay much more to get 18 cores, or only slightly less for much less cores.