I made two of these this weekend. I got the pattern at Joann's for 1.99$. The pattern called for a yard and a half of quilted fabric. Quilted fabric is quite pricey so I made my own. I used a cheap muslin on the back, the cheapest batting I could find, and for the top I spent a little bit more on a print that I liked. I had to spray baste all three together and then machine quilt it. Then I could finally cut out the pattern. I love how they turned out.
Did I mention I found this car seat for $2 dollars at a yard sale?