Macwage, I may be mistaken, but you are asking much of the kiltmakers that post here. You are asking if they will share there sources of kilt material with an amateur/new competittor. I think that most would respond to polite, private inquiries about the source of a particular tartan, but you should be tracking down suppliers on your own if you are expecting to make kilts for sale.

I admit my opinions may be completely off-base since I am not a kilt maker, but they feel appropriate to me.