For under $50.00...that's within just about everyone's budget. I don't have pics yet but I will lay out the parts list. Tomorrow I will take my camera out with me.
The motor I am using is from a 14.4 volt cordless drill. I got mine on Ebay, minus the battery and charger, for $9.99...shipping was free. If you have a flea market or Salvation Army thrift store nearby you can pick these drills up for a song, people buy new ones when the batteries die. The drill I am using has a 21 step clutch which will protect the motor if I am not there when the table reaches the end. The lowest setting seems just about right.
For a power supply I grabbed my old car battery charger. It has 2 amperage settings on the 12 volt side, 2 and 6 amps. It will also do 6 volts at 5 amps. It is fan cooled, fused, and designed to run for long periods...perfect for my needs!
For a motor controller I tried adapting the drill trigger but it just wasn't sensitive enough for the kind of speed control I wanted. I went online and found this:
http://www.electronickits.com/kit/complete/motor/k166.htmI spent a couple hours last night soldering it up. Even with my limited electronics skills it was dead easy! Just use a multi-meter to identify the different resistors...the board has the values silkscreened on it so you know where it all goes. I tested it tonight and it runs like a champ. Left over from my days as a PC tech I have a bunch of nylon posts for mounting motherboards. I will use 4 of them to isolate the controller from the aluminum box so I don't short it out. I will also add a 12 volt fan from an old computer case to the motor/controller enclosure to keep it all cool.
The bi-directional pot is nice but I will be adding a power switch just in case. If you don't hit the sweet spot and get the pot in the OFF position it can sit and draw current and likely burn itself out. I like the fact that the battery charger has a meter on the face so I can see my current load. Thet will let me know if I am pushing things too hard.