I personally wouldnt buy anywhere else but JCrows because he is listed as the supplier for Gerson patients on the Gerson website and checking out those other links given (of which some are old/product unavailable btw), I find that theirs is either for fish tanks or there is no detailed product description. I dont trust them.
I find $55 for 16oz still a great price - it lasts many months, and thinking about what some things in daily life cost its nothing.