Outdoor Master via Amazon offers the OutdoorMaster 180° Snorkel Mask in several styles from $44.99. Coupon code "SNORKM30" drops the starting price to $31.49. With free shipping, that's at least $14 off list and the lowest price we could find. It features an adaptable inner mask, adjustable rubber straps, and a carrying bag.

Update: The GoPro Edition is now available in several colors (Ocean Camo pictured) for $54.99 before coupon, $38.49 after.