AFAIK, you can order potassium tetrachloroplatinate (or tetrachloropalladate) from Sigma-Aldrich or any reseller working with them... The problem is sourcing iron(III) oxalate (ferric oxalate); you can't find this easily (because it's an ill defined / highly variable compound with very few manufacturers), I ordered mine from B&S. (I'm in Istanbul, Turkey!) If you have problems in finding ferric oxalate you can opt to try pop pt/pd printing. In this case you'll have to order ammonium double salts of pt or pd plus ammonium iron(III) oxalate as sensitizer. Ammonium iron(III) oxalate is a well defined compound and you can find it from Sigma-Aldrich or other sources. See Mike Ware's articles for more information.