Which type, the one with one knob and a display, or the one with 9 or so knobs??
This:
Is a WSME type, sold under much names, and buying one I would probably take the cheapest one I can find (which usually is the GIANT brand, in Yellow)
This is quite an old model, probably all the small kinks that plague newer models are ironed out, and parts are cheap and plentyfull.
Complete circuit boards etcetera are available from Aliexpress
Or this:
This looks like a newer model, and is also found under several names , like Welbach or Rohr.
German sounding in name only, also Chinese, but probably a more modern design internally as well.
At these prices I would buy the cheapest I could find with the same design.
You could also look for a NTF Supertig 200, it's in the same price category, but is generally regarded as a good machine for the price.
I had one as a temporary replacement for my main 240v welder, and I could not fault it, and haven't heard problems from the person I sold it to.
(Rtech sell the DC only version at quite a hefty markup, so the NTF design is probably quite good, as Rtech don't go for really cheap designs to resell )