I'm on the fence over this one. On the Mustachian side could potentially find great deals and save yourself some money in the process. That I'm all for. Unfortunately it gets a little tricky. Pawn shops can also be home to stolen goods, this here is where morals come in to play. Would you buy something knowing in high probability it was stolen? For example, tools. Numerous occasions tools have been stolen from contractors on jobs I've worked on. In one case the power tools showed up at a pawn shop a month later, complete with the acronym of the contractor still stencilled on them.
This is just experience talking, if I never worked in a trade I likely would buy them without thinking of their origins.