It depends on which model you get and what shape it's in. If you get a nice model that has a pinned barrel and counterbored chambers, and, if stainless steel, chrome-plated hammers and triggers, then it could pull down $500 or more.
A good Ruger Security-Six might also be a good alternative, if you can find one. I've been looking for these at auction sites and they seem to have dried up.
These medium frame .357s are, in my view, the greatest revolvers ever made. The larger 686 and GP-100s are just too big and heavy to carry and shoot in the field. Years ago, I had a friend who had to shoot a charging couger (it was rabid) while he was inspecting fence posts. He shot it with a Dan Wesson he carried in a shoulder holster. He later said he was glad his barrel wasn't the heavy type with the underlug. Picking up a moving target is easier with a lighter barrel. As it was, he was shooting a 6-inch barrel!
I wish S&W and Ruger would reissue their medium frame .357s.
I'd love to have one of the early S&W 66 revovers with a 4-inch barrel.