I followed all of ballerina's recommendations on where to get the different parts for tDCS treatment. I got the activa dose unit that she linked to...it was $225 I think. I also had to purchase TENS lead wires with pin connectors (the activa dose machine only comes with snap connection wires and those won't work for tDCS)...I bought these from amazon.com for $4.96 including shipping (actual price was only $0.01 plus $4.95 shipping). Then I bought the sponge electrodes seperately from the site she recommended along with addition sponge inserts. The only other thing I had to buy that she did not list (but someone else did) were two "pin to banana" connection adapters. These were just a couple of dollars. All together I paid only about $300. I did need a script from the doctor for the tdcs unit but all the other stuff I was able to order without any special script or anything from the doctor.

As to why the Iontophoresis unit...it is just what is used for tDCS treatments. I'm sure someone else can jump in with the technical details on WHY it works but I haven't heard of any other sort of unit being used for tDCS. I was a little confused by this at first myself because I thought it would just be called a tDCS unit or something...but it's probably not a common enough use of the device for there to be a change in the name or anything.