Hi chris, im trying a anodising company at the moment for some bits. duno if they can do aluminium nuts for you. would you like me to ask?
Also you could cheat on the front end and use FT axles with a purple cone washer
or try these seeing as they do have purple nuts in the picture
http://cgi.ebay.co.uk/BLUE-ALUMINUM-...4.c0.m14.l1262
westw00d