Don't know your placement (bow or console) but I recomment the ram mount recommended for "rugged use" with a 1.5 inch ball. I have a 788 and have the 1 inch ball but it gets loose whenever I hit a decent wake on plane (bow mounted). The model you want is the ram 107 U and not the B-107U which is "light use"
I just bought one on-line at www.themountdepot.com for $57.25 including tax and shipping.
Also, on the 107 U the handle is larger, allowing a lesser effort to tighten and loosen. Make sure you loosen or remove the unit when not in use to save wear on the mount assembly.
Willie Island Cove Marina has them for 48 if they are still open. You should call them and see or try ebay you can find them there delivered for 50 or less.