http://www.watercoolinguk.co.uk/catalog/index.php?cPath=63&osCsid=c11940f4d656bd38e06be8df86f25d43 and http://www.aquatuning.co.uk/index.php/cat/c490_Thermal-pad.html (have various websites, look for one where you are located) stock some pads, not sure what thickness you need however, good luck :)
I remember seeing a post a long time ago where someone spray painted their motherboard and it worked just fine, so I suspect a tiny bit of spray paint won't do any harm :)