Buy white PFD (prepared for dying) 100% cotton fabric. You can use a 40% off coupon at JoAnn's. I think it runs about $7 /yd. Don't use the cheapest muslin. Look at the fabrics, and touch them to choose the one you want.
There are ways to prepare your own, but I haven't done it myself. I'm sure your husband's business has the equipment to make the print last.