[Elecraft] Power source/supply for k2 testing

[Dennis Vavra]

I have reached the alignment and Test, Part 1 Phase of const of k2. On page 42, right column, step 2, it calls for a power source.
Could anyone direct me to a relatively cheap but reliable power supply (Radio Shack, etc) give me model#  etc...Also could I use a Gel cell batt 
for testing? What do you all use??  Dennis Vavra,  AD5LY