Good idea waiting for a used one. Be it not quite what you have in mind but,.... I bought a used one from the local junior college . It was a P&H machine (a really long German name) that probably wieghs about 1000 pounds and has 400 amp capability but at the same time very low settings as well. It came with a chiller and a foot pedal, I just had to but a 250 amp W/C wand and a regulator and was in business
It maybe old ( 1960's?) but it has all copper windings in it and is anolog, which means I can fix it
All for $175 before my torch and reg.
Cheers,Steve