I know there are math formulas to figure it all out but my general rule of thumb is to at least double what I spent on ALL materials used to make the quilt then add about $30 handling fees. For the quilt you have pictured I wouldn't go lower than $175-200 then if you feel like you need to put it on sale you could go to $150 but that is a steal of a price. Just because it is a hobby for you and you would do it if no one paid you doesn't mean your time isn't worth anything. I would definitately try to use your mom's tax id to purchase materials at wholesale--of course only on the material that you are going to use for selling quilts ;-)
Good luck on your adventure