Kohl's has many hats regularly priced between $20 and $24 on sale for $10-$16. Coupon code takes another 30% off for Kohl's charge card purchases. FW CB is 2% (may not combine with coupon code). Shipping over $75 is free, one hat is unfortunately about $6. Hopefully better shipping codes become available.
MLB has the best selection and prices overall. NHL has good prices (almost always $7 AC), but pretty limited selection (sorry Phoenix Coyote fans). I only spot checked NCAA teams because of the sheer number: when teams had hats, they were all $11.20 AC (I guess they justify the higher price because they have to pay the athletes salaries...oh wait, never mind). Still, it wouldn't surprise me if some of those were $7 AC as well.
EDIT: Also found some cheap women's team jewelry. Necklaces as low as $4.90 AC and earrings as low as $6.30 AC.