I picked up a roll of c110 from a contractor supply store. It's pretty thick, and rather heavy, but I understand that it's +99.5% pure Cu. I used a roto-zip to buzz through it, and a old vise to flatten the plate out. The are all just a little bigger than the heatsinks.
Anyway, I'm not sure about the hardware store making you a 'base plate' for the heatsinks. I'm sure there's a machine shop somewhere that would do it, but you would probably pay the same amount for a dremel down at the store.
I've never used frag tape before, always arctic silver. I mixed some AS with the AS adhesive, and glued on all the heatsinks to my memory chips, along with the gpu hsf. From what I understand, it's supposed to come back off without a lot of prying/praying. I'm not sure what kind of results you'll get with the frag tape.
to 5v.