Joann's has it in the apparel area. I recently bought some for a quilt. I've just started working on charity quilts for Quilts for Kids and their website says that they need quilts for teenage boys. If you walk through the quilt fabric at your local store, you can see why - it's all pastels, and hearts and butterflies. There's almost nothing for older boys. I made a very simple quilt (just large single blocks) from camo fabric, a fabric with autumn scenes, and a fabric with wildlife animals. I picked a handspun plaid at Joann's for the back and later realized that it reminded me of the inside fabric in sleeping bags.
One reason I used just large blocks is that cutting the autumn scenes and animals up would make them difficult to recognize. And (speaking for myself) guys like things simple.
Tate