ive done lots of store displays for a couple shops here in Michigan-
one shop gives me a kit & pattern to make- then the same amount of fabric for me to make a second one if i want- or i can just have the fabric for what i want- and i get to keep the pattern-
another shop pays anywhere between $50 & $100 for the top only made- i get to keep the patterns & scraps-
and the 3rd shop i work for pays me (again between $50 & $100) and lets me have the finished item when she is done using it-
so---it is really up to you & what will work for your situation- do you want to give up the quilt after the display is over? would it be more cost effective to just give fabric instead of $$? do you want to just pay someone and be done with it?...you may want to talk to to your display sewers to see what they might prefer too- i tend to do more sewing for the shop that pays me & lets me keep the scraps & patterns (she is very generous when she puts the kits together- and includes everything necessary- thread, fusable if needed, freezer paper if needed- anything that is needed to make the project- i do enjoy making for the other 2 shops too- when they need me to do something...i think all 3 shops have good ways to do it.