I have one of the rinky dink (but still expensive) "battery charger style"
weld cleaners- mine puts out 40 volts, about 10amps. It will work for cleaning discoloration off of welds. It will not do anything to forged stainless, which is dark gray all over. Its good for jobsite work, where we just need to get rid of the blue.
The Walters are better, I am sure- but, as you mention, German Pricing aint cheap.
If I was seriously considering a Walter, I would bug a salesman until he brought one to my shop and demonstrated it. For that kind of money, I want to see it work. Walter has outside salesmen, who service big accounts. I have talked to them a few times over the last 25 years or so- they are usually pretty knowledgable, and, given that to them, a decent sized account is measured in tens of thousands of dollars a month in sales, they are unlikely to bug you later- its more about you bugging them, til they actually show up with a demo model.
I have found there is no substitute for amps, and heated acid. I send all my actual electropolishing out to some guys who have a hot-tub sized tank of 100 degree phosphoric, and a 1000 amp 100 volt power supply.
chromium oxide is tough stuff.