To give you some comparison, my aunt in Kansas charged $50 for full size quilts all over pantagraph, no speical quilting 35 years ago and had a lot of business. And even then she complained she wasn't charging enough-she provided the poly batting- the customer had to provide the backing.
Good think you have some resources to check with on pricing. Maybe you could rent time on your machine for those to quilt-maybe $30 an hour?
Do not under value your work. It will come back to haunt you, it will sap the joy out of quilting and then you'll still get demanding people who aren't happy with the work you've done.
"No" is such a freeing word.