I would charge $10-15 per shirt. 9 shirts - small quilt $90. 25 shirts - big quilt $375. Go with the $10 if its a straight set no sash no border. $15 with sashing and borders (I like a nice little scrappy 4 patch as cornerstones)
If you do it for free, what you are saying is your work has no value. Gifts are one thing but if they ask you for it its not a gift.