When we did our plumbing, 1" Synflex was special order and much more expensive than rigid copper. And 50 CFM requires 1" And Synflex isn't forever either. That is why I buy it by the roll for replacement on our trucks. It is especially vulnerable around bends. However, If I just used only one or so air tool at a time, I would consider this 1/2" hose.
http://www.ryderfleetproducts.com/tectran-1928-05/airbrake-tubing-1-2-red-per-ft-ttm-p-ttm-192805

75¢ a foot is about as good a price as I have found.