NO....first off...his buying materials means what...you can't buy materials until you know what you are going to make!
Are you planning to do more quilts like your sons? Then you need to copyright your designs...if they are copyrightable! If you have never done consignment or piece work you need to find someone who has and talk to them about what to expect. Sadly you will find that we will be working your butt off and will have little to show for it in the end. Especially if you are splitting the end monies with someone!
AND just whom is he planning to market your quilts too?
Is he able to target an audience that will shell out $200 for a baby quilt? Remember, even if the cost of materials is covered by him, he expects to double that for a profit...so that means you do all the labor, at say $10 an hour, and then you have to double that for a profit.