Not a penny less than $350 (and add another $50 if you're going to send it out to be quilted - ithat way, if it costs $100, you're still going to make $300 to cover your time and supplies).
Don't sell yourself short. Remember, it's going to be family heirloom. Priceless. ;-)
And I would love to see a pic of your quilt straight on - you don't get the full effect when it's laying on the bed. I think it's fabulous.