I followed ballerina's recommendations on where to purchase the unit. It is on page 2 of the tDCS thread, post #20:

http://neurotalk.psychcentral.com/thread160980-2.html

I did need a Rx for the unit to purchase from this particular website though. I have heard from others that there are places you can order online that don't require one...but I don't know which ones those are. I did not need an Rx for anything other than the unit itself though. All together the cost for the unit and the other materials was about $300. I did all the treatments on my own. I have outlined my current protocol many times on the tDCS thread but if you have any additional questions, please feel free to PM me about it.