Dick's Sporting Goods offers the Field & Stream Men's Polarized Sunglasses in several styles from $9.99. (Prices are as marked, although not all items on the page are on sale - some are at list price.) Opt for in-store pickup to avoid the $5.99 shipping charge. That's at least $5 off on the discounted styles and the lowest price we could find. They feature full UV protection. A couple of best bets:

Field & Stream Men's Pointer Polarized Sunglasses in Brown for $14.99 (pictured, $10 off)

Field & Stream Men's Burbot Polarized Sunglasses in Camo for $26.99 ($8 off)