The AC adapter used on the Apex base module is different from what is used on our previous controllers. It is a 12V DC, and at least 500 mA. If you can find one at Radio Shack with the right connector (2.1mm female), and right specs, then yes it will work.
I picked one of these up at Walmart this weekend for a fan. It has a selector on it to select mutiple volatges and comes with I think 6 different connectors. The one I got was good for 1300 mA. The one I bought was $18.00. They have one rated for less mA which will work for the APEX and cost less than the one I got.