Well, I don't know if it's the best place, but I picked up mine on eBay. Mostly, there's new ones for sale, which are no deal, but if you wait long enough, you might run across a used one. The better deals are usually on presses being sold with several caliber setups - if you need those calibers. Expect shipping to be expensive.
Might be worth finding forums for high volume competitive shooters (USPSA, IDPA, etc.) and checking out their classifieds.
Good luck - took me a couple months to find mine!