REI Garage offers the Outdoor Research Helios Sun Hat in Olivine for $17.73. Opt for in-store pickup to dodge the $5.99 shipping charge. That's the lowest price we could find by $2. It features a foam core brim for flotation, 50 SPF sun protection, sweat-wicking browband, and adjustable drawcord.

Update: It's available in size L only.