I started with an 8.5v 5 amp power supply I think it was. Then i switched to a 6v 2.5 amp I would like to slow it more but need to get a motor controller for that.
I don't have one, and just started looking around a little today lots of different ones makes it confusing. I figure something out. I need to work on the arm movement some more as well.
You don't need anything fancy. These work great. I would suggest using a 12 volt power supply with them though, I have heard using less can cause issues and noise. I use these ones with 12 volt supplies and they work great. You can turn them down to a crawl and still get plenty of torque.