Rhonda,
good question---I sell "customized" kits, a customer chooses the design, and the fabric he/she wants in the kit, sends it to me (the fabric), I cut it with my die cut machine and send it back, along with any leftover fabric. I don't send any instructions, though, so the quilter needs to have enough experience to look at a block and be able to tell how it is constructed.
I also sell applique by the piece. Some customers have purchased as few at 25 pieces for a baby quilt, placemats, etc.
It's all customized and very flexible. I have quite a few quilt selections on my website and am adding more applique all the time. The applique is time consuming, though. I haven't figured out how to put an example of an applique piece on my website without actually making a sample.
After the train applique is finished for my son, I think I might buy a few Hawaiian (spelling??) appliques. I think that might be challenging. Needle turn applique is a skill I need to improve.
Rose Hall