They are very common to find used, possibly even new now but part of a large cluster package. Most will say, unsure if works, untested, worked when taken out, all of which may be accurate but not tell you if will work when you get it so still a lottery but most are good. Look for units that are clean, have good condition faces and readings, no rust on case, font matches your unit, that sort of thing and you may get lucky, or at least some nice spares. Temperature sender units are also cheap, doesn't hurt to grab another even as a spare.
