You don't absolutely need one. I haven't used one in years. What this means is a couple times a year I have to trim off an inch or so of dry, cracked breathing hose. So now I have a 49' hose instead of a 50' hose. 'Course, I use my hookah 1000+ hours a year, so YMMV. Probably best to have one, but not critical.
You can find everything you need online at www.supersnorkle.com
They sell the same recreational-level, stiff, floating, yellow air hose all the other manufacturers do. If you want something better, your local dive shop can hook you up.