Although he doesn't have a website you'd have to travel a looong way to find a nicer guy than Leigh Knudsen, aka email@example.com. He runs Mar Machine in Southern California and he has a great collection of used tools for sale. Contact info:
Attn: Leigh Knudson
c/o: Mar Machine
719 Ohms Way Costa Mesa, CA 92627
Machinery Journal is a free monthly publication that has a compendium of used tool dealers in the United States. I found Leigh here...
Punch Press News is the best I've found, but their website had changed and Google didn't help. Their twice-monthly print version is alphabetized according to type of machine you are looking for, too.