I just ordered a kilt from Keltoi Gailic Clothing (Slohairt here on XMarks) that requires a custom weave. My cost for the 8 yards custom weave and kilt is almost $800 Cdn. The material is 16oz from D.C. Dagliesh and is single width only. I would order enough for your kilt and fly plaid at the same time as ther is probably a set up fee and up to a 3 month wait even if you can only afford the kilt now.

Unless you are making the kilt yourself I'd suggest letting your kilt maker deal with the ordering. Keltoi allows me to pay half up front and half when my number in his kilt queue come up which does make ordering easier. Matt (M.A.C. Newsome) at Scottish Tartans Museum, Barb Tewkesbury (Barb T.), Keltoi (Slohairt) all offer quality hand sewn kilts and are all members here. All are first class and do excellent work.