That's my addage on this one. Personally, I plan on living in my home for a very long time. (Right now, my first house is my last one ...) Anyway, if you spend a few $$$ for pipe insulation/wrap, you'll definitely save money. Morally, I guess it's the right thing to do.
If your pipes are near, say, a cold outside wall or in a cool basement or get lots of 'use (from hot water running through them), then I'd insulate them. Depending on the size and type of piping and purpose will dictate what you should wrap them with. Do some measuring and analyzing and head to the Home Center.