Where to buy heatsinks/thermal paste/ etc...

Well I am working on putting some passive and active cooling on my motherboard. Specifically a HS and fan on the south bridge, and some heatsinks on the mosfets. I just put a fan on the Northbridge. Man, the southbridge gets the hottest out of all of them! It will (almost) burn your finger if you leave it there a few seconds.

Anyways, back to the question:

Where can I go to get random sized heastsinks for low cost? The regular Walmart, Bestbuy, CompUSA (UGH!), etc doesn's sound like the right choice.

Would RadioShack have any heatsinks?

Also if I can't find the "exact" right type of heatsinks, what is the easiest/best way to cut them CHEAPLY?

If I have to buy a dremel, sigh, I guess I will, but if there is another way to reasonably cut the metal in a straight line then please tell.

Also, let me double check this.. Copper heatsinks beat all right? (Compared to aluminum, and god forbid, steel.) ?

Thanks a ton.

well i would try plycon.com and frozencpu.com if not just use cpu coolers and if you have a connection at a machine shop you can get whatever you want.

~Will