The first place to look, and a place to receive some information on pricing is the Simpsons web site:
http://www.simpsonltd.com/
Prices here will be on the high side. This is a reputable dealer, beyond question. It is possible to negotiate a price provided the pistol of interest is not on consignment.
There will be other sites provided, I'm sure, but I am not as familiar with them.
David