Another place to look is your local laptop store. My current laptop, as well as its predecessor, are refurbished ThinkPads I bought there for about $300. They run Linux just fine.
"Local laptop store?"Not quite sure I've heard of such a thing, at least not recently. My Chromebook came from BestBuy.
As it happens, my beat-up old DOSbook (an old Compaq Contura 486) crapped out on me, a couple months ago, and I'm looking for something of about the same physical dimensions (or a bit smaller and lighter) to replace it. Something old enough to have a floppy drive and/or a PCMCIA slot, and to run DOS and DOSapps without a problem.
-- JHHL