Patching a patch?

Are tubes super expensive in the states? I reckon a patch kit is great for getting you home (much like the frame pump philosophy). But once your home - spend the $2 and put a new tube in.

In fact I ride with a spare tube in my saddle bag - along with a patch kit just in case I have a shocking run of luck...or happen to ride through a car accident involving a truck carrying thumb tacks...