It would depend on your longarmer. The longarmer I was using we never put it in writing. She bought batting by the bolt wholesale so I always just used hers. It was about the same as a good sale at JoAnns. SHe usually had several different choices of batting. So may designs to choose from it was almost overwhelming.
The longarmer I use now I supply the batting and backing. SHe has basic colors of thread, if you want something fancy in a thread you bring your own. She has done 2 quilts for me so far and has done an excellent job and her prices are good. No contracts. She is a member of my guild. One quilt I just told her to do whatever she thought looked good. The second quilt I just picked up today. I told her I wanted something like interlocking squares or geometric. She must have read my mind because she did exactly what was in my vision of what it needed.
You have to know them. Otherwise I would want a contract.