Most people don't appreciate good craft work, but for those who do you shouldn't have a hard time selling it.
I would say easily $550.
When I was at my local quilt shop, people were coming in and asking how much to quilt the tops they had hanging on the wall that were for sale. Mainly, how much to have it completly quilted. Kings ran $1200 and the people didn't even flinch when she quoted them that price.
Check with your LQS and see if they will put it on consignment for you. Get the figures and what your coming home with so there are no surprises.
Let's face it, we as quilters know the time, effort, cost of what we are making and we do it because we love quilting. For those who don't know what we do, stop in at quilt shops and talk with the long arm quilters or the staff. Nothing can be made better and you certainly won't find the quality at large chain stores.
Good luck and keep us posted on the sale.