You know this is really amusing to me because I had to go out and buy girly fabric when I needed to do one for someone expecting a girl. I had all sorts of boy stuff because of DGS but no fleece or flannel that was pink or even the least bit girly. Even DD and DGD don't like pink!
You are correct, there's lots of little boy prints available, as well as camo/hunting type and sports oriented fabrics, but if the older kids/adult males like things like skateboarding, motorcycles other than Harley Davidson, even Nascar is hard to find, you are out of luck in the stores I've been to.
However I've found that guys in general can be quite pleased with plaids, bandana prints, and such. Good luck on doing the more 'manly' quilts!