Nothing exactly what you are after, some are close, my comments.....
Toronto Surplus (
www.torontosurplus.com). He's a really nice guy if can get there in person but hard to connect with. Massive inventory of test equipment, prices are 10x what the go for on ebay. His business is selling to some university/business lab that needs an exact replacement for some piece and gladly pays 10x the price to transaction with a professional business and get a warranty. He does have an area with lots of control electronics and imo is the best bet.....the challenge is getting to him, doesn't make himself super available.
Sheffield is a bit of junk store, but has lots of stuff. Definitely slumming it from Mike @TS above ( I think thats his name). Pricing is not marked so you have to ask, and he uses the Heisenberg pricing model - showing interest in an item may change the price of the item.
A-1 Electronic Parts, bottom of the 427. Bit of junk store but lots of electronics stuff. New electronic components. Unlikely to have what you are after, but lots of used electrical stuff.
Kitchner - there's (or was) an electric motor repair shop who has a ton of stuff. He had a separate warehouse with transformers. I walked out of there with every to build a RPC and step up to 600....including transformer, box, motor, contactors, caps, etc. It was a long time ago and I can't remember which one (Possibly Dynamo?) but....if I was on a mission I'd start calling electric motor shops there asking if they can help you with used ______.
There are few vendors of used transformers that come up on a search...long shot but maybe worthy calling
Sayal is new electronics parts, some might be surplus, but your not going to find used power and control stuff there.