I have been testing this pulsed unit for the past 10 weeks "Ultra-G Digital Galvanic Stimulator" against the non-pulsed Fischer md1a. Amazon has it for $249. I paid $140 about a year ago. I've been testing this machine for awhile now. I'm just doing a more accurate test using one machine for my left hand, the other for my right hand.
So far the results are identical. Each hand seams to be responding exactly the same. If you search the net, you'll be able to find this machine for under $200. You'll just need to adapt your own trays and buy some female banana clips at Radio Shack.
I've been doing ionto for 7 years, most of that time using the Fischer unit. The pulsed unit is way more comfortable to use.
Of course you can spend many hundreds more for the "Big Name" machines. All galvanic machines use DC current.