You should charge
amount of time X $15.00 hr + cost of materials = $
You could "guestimate" the amount of time from the lap size that you have already made. I think your price (if you figure it this way) will be much higher than the suggestions I've seen posted. The above "formula is used for "replacement of quilt" (insurance) appraisals. I don't know how it is figured if you wanted to "sell" a quilt, but the final figure would be much lower. Hope this helps. And will be curious to know what you decide to charge, if you will be posting that information???