When I price mine, I figure out how much fabric and what it costs. I was told that even if I got the fabric on sale to charge full retail price (That way, if someone else were to want one, and you couldn't get it on sale, you are still able to charge the same price). I figure out approximately how long it will take (I have started keeping a log), and then I find out how they want it batted (again, I charge full price, just in case I can't get it on sale), and how they want it quilted. I find out what my LQS would charge or a LA would charge to quilt it for me, just in case, I can't do it on my machine.
I have looked on etsy when trying to price a quilt, and the prices vary, so that is a tough way to decide on pricing.