There is quite a community of second-hand breaker dealers.
You would be astounded as to how many ancient 3-phase breakers are available -- reconditioned -- off the shelf.
You can do an eBay search, a Web search, or hook up with known players in the marketplace.
Salinger (Michigan) immediately comes to mind. There are three outfits within 120 miles of my shop that deal in 2nd hand breakers, odd fuses, etc.http://www.salingerelectric.com/
So, before you knock yourself out, pick up a phone. You might find that you can negotiate your price. It's not as if this stuff just jumps off the shelf.
Lastly, if you come across decent gear that is being replaced, these are the folks that buy such gear. It beats throwing the stuff away. The chance that a small EC is going to find a home for such gear is nil.