Dave,
most important aspect is what spring rate do you need for your weight and riding style, after that there is the debate on Linear vs Rising rate springs, only then do you need to choose the source of springs.
but if you have sorted the first 2 of the above, my not very helpfull advice is that you get what you pay for.
I took the short cut and had a suspension [and firestom] specialist rework mine with springs and damping to suit me, so I dont know who he gets his springs off, but I do know they are linear.
Contact Roger at Revolution racing if you want to go down that route, or even ask his advice on fork set up.
http://www.revolutionuk.co.uk/.