I purchased my hot glue gun at my local hardware store. Works fine, also they stock the appropriate glue. I did not buy the most expensive one but the gun doesn't do much just heats up the glue and provides the delivery system, and the glue is always covered up by scenery.
I generally use the glue gun for adhering stuff to the benchwork. I haven't used it for track. Mainly for adhering screen to wood, or cardboard to wood.
Dave LASM