Surplus Sales has been around for a while so I guess they have a large enough inventory and customer base to survive. Not sure about the other sellers but It looks like electronics is making a little comeback as a hobby, so there might be a reasonable market for this stuff. All Electronics had a retail store which might be what dragged them down. Brick & Mortar operations have a lot of overhead, tough to support with such a niche market.
The nature of the demand has changed as well, so those that weren't nimble enough (or had too much inventory) can get caught up short. When I was younger we'd all pay a couple hundred dollars for a 70lb Tektronix 'scope that was woefully out of date, but still usable. Today you can get a pretty decent DSO for a couple hundred bucks from Siglent, Rigol and others. That's gotta be killing the market for all that old test equipment. Really power supplies and maybe signal generators are the only thing I'd still even glance at. Hard to beat those old, quality, power-sucking analog units for creating nice clean power and signals.
