I got a written off office HP LJ 2500 from 2008, around 10yrs ago for 30€. I added a RaspberryPi for wireless zeroconf/Cups printing. It hasn't required any refills/maintenance yet and is autodetected on Win/Mc/Lin/Android.
Super happy with it, I print a lot of postage labels and other stuff with it.
My 4050 with duplexer must be 15 or more years old. I once had to re-solder the JetDirect network card in the stove. Hooray for the Internet and the kind person who posted that. Apart from that it just works. Can't beat it for correspondence and everything that can be printed b/w or gray.
Super happy with it, I print a lot of postage labels and other stuff with it.