You can buy RAL colour fans easily enough too mate, but they don't tend to come cheap. There are the classic 4 number sets and a more comprehensive 7 digit range. Most of your general suppliers will recognise the 4 digit range and not the 7 so I'd stay clear unless you really need a wide range.
I use them every day with my work. There's also a good website that will give you a conversion to rgb values, I think it's ralcolor.com but will check when I get to work.