Exclusively for Prime members, Amazon offers the Irwin Vise Grip 18" Locking C-Clamp, model no. 22, for $13.11 with free shipping. That's at least $9 less than you'd spend at a local retail store. It features a 8" jaw opening, swiveling pads, classic trigger release, and turn screw pressure adjustment.
Note that although this item is currently out of stock, it can still be ordered at this price with an estimated in-stock date of February 25.