Need Some Electrical Expertice

[nachoman]

If it was $28, that is a great price for a 5 amp DC supply.

Depends on where you buy it from. A dedicated model railroad power supply will run you much more. If you are crafty, you can find a more generic power supply or salvage one from another appliance. A 12v auto battery charger could work, as could power supplies used for electronics hobbyists or computers. I have one that I hauled out of a dumpster, and all I needed to do was move one wire over and replace a fuse to make a 12V AC and DC supply.