Any chance to buy locks in London?

I got a new hobby: lock picking. For obvious reasons I won't just pick random locks on the street, so any chance that there is some secret lock picking store in London I don't know about selling used locks to train on? I live near Zurich, but buying a lock there is usually 15-20 per lock which at some point will me leave bankrupt. Because I am in London at the moment I wanted to give it a go...