You can pick up good old body hammers and dollies at swap meets, flea markets and antique places for $5-15 each. I probably have 2 dozen body hammers and only bought one Martin brand hammer brand new, a design I couldn't find used. Quality hammers are forged and hardened. Cast hammers are usually soft and don't work nearly as well. When looking at used hammers if the face is marked up a lot chances are it is cheap and not worth the money, same with dollies.
Grigg