What manual valvebody for my 904?

Seems like everyone is happy with the valvebody they bought! I'm always watching for deals, I'm on a TIGHT budget, so I was wondering...is there anything wrong with used valvebodies? Should I do anything else with the transmission when I change the valvebody? It was rebuilt with a mancini kit and deep pan. Transmissions for the most part are still a little bit mystical to me, I've never done anything but shift kits.