the problem with second hand stuff and in particular timber, is a tuppenys worth of second hand wood can bu99er up a £90.00 circular saw blade in seconds.
From a punters point of view......I recently had an electrician in to do the wiring for a garage conversion. My consumer unit was obsolete, so to add the new breakers would have meant a whole new consumer unit = more cash. Spark said "I've got a whole stash of stuff at home.....I'll see what I can find"
Long story short, he found some second hand breakers - demonstrated testing them to me so I knew I wasn't going to burn the house down, and left me with a much smaller bill.
I was happy.
Many years ago a customer wanted a large 3-storey house converting to bed-sits on the cheap. I rewired the whole lot with 2nd hand cable, accessories and CU. Even 2nd hand screws & Rawlplugs, just to prove I could. And of course make the job worth doing. As I said he wanted it cheap.
Couldn't get away with that today!