Okay I'll confess. I own an "Ltec Heliarc 250HF pf Square Wave" that's semi-retired, although it's perfectly functional. Good old rugged built machine, running on 480v, probably never had the cover off. Esab probably still supports 'em, at least with manuals and parts lists. The machines probably use very few proprietary parts that couldn't be substituted - if it ever needed them.
Unlike some other machines living in a dirty environment, the panel's rheostats, switches, and twist knobs have been trouble free.
I never used it for heavy work, like high-amp stick or carbon gouging, although I'm sure it'd run at max duty, no problem. Most recently it went on loan for "government work" repairing an aluminum boat. I may have some pics of the boat job, but you know what that's about anyway. For sure I can post a picture of the machine.
One nice feature is that the welder is compact and narrow in width, thus easy to move around a crowded shop; much more so than Dialarc or other "big box" machines.
Today's price? I'd say $400 - $700 depending on condition and extras.
For $500.00 I give it 4/4 thumbs up; especially if mobility is important.
Personally, I'd bet on a 250HF to outperform and outlast a brand new "economy" machine and would prefer one over a new import.
Good Luck