i build my own dice pot and i would like to see how it works on one of my older pentium d's. i got some plastidip and am now realizing maybe that is not the best solution. i would like to try to get all the stuff locally and not spend to much
im assuming your question is "where is the best local place to get some kind of conformal coating?".
in which case- you can use any non-rigid potting material, dielectric grease, silicone, liquid electrical tape, etc. if you are "only" using dry ice (~ -50*), you dont need to worry about the physical properties of the material at negative several hundred degrees, as you would with LN2.
if this were a brand new I7 system, i might spend some extra cash and get the good stuff, but just messing around with a cheap older system, you can get away with cutting some corners without much risk.