They come up pretty commonly at thrift stores here and at flea markets. I've passed up some nice ones like a 1991ish TOL model with variable speed and the dual stage Lamb motor. As well as a straight suction one from the 60s at Habitat. Mostly because it only had a few attachments and the hose, yet they wanted $35 or something pretty high for it. It was in practically mint condition though so maybe they realized it was collectible.
My main Kenmore I'm looking out for is one of the avocado PowerMate ones. That was my mother's first vacuum back in the 70s, ironically she got it at of all places - Goodwill. She's bought Kenmore canisters ever since, other than a few uprights here and there to supplement them.