Welcome aboard. Oh, how I remember looking for that high protein (gluten) flour. I tried the one you mentioned on only one occassion a long time ago and have steered away from bleached flour ever since. You can get much better high protein flours if you're in the SF bay area. The stores below might be in other places in CA.
Pendleton Unbleached high protein (13.5%), used by very good independent pizzerias in area, is available at Cash & Carry in 50 lb bags, $8. You'll see Fisher on the purchase label, which is the actual miller that Pendleton purchased, and then you'll know you have the right one. If you're looking for more of a pull and chew of a pizza, you'll find it used by Pyzano's, which is owned and operated by USA pizza team manager (Tony G)-- if he can win a few world championships in Italy tossing the stuff, along with national pizza tasting championships (I prefer his thin option), you might say it will hold up as well as any. If you have a chance to get over to Castro Valley on the East Bay, he's a worthwhile guy to stop in and see.
OR, you can get Giusto's Unbleached High Performer (13.5%) in nice small 5 lb bags at Andronico's in Los Altos. It was on sale recently for $2 something. Talk about a well-hidden secret. I'm not surprised that Chris Bianco uses Giusto's as one of his mixed flours. He's one of the world's premier pizzerias, highly respected by P. Reinhart (author of American Pie), and winner of the James Beard award. The guy does all his kneading by hand, despite serving a huge audience near an arena that waits hours to get in. Giustos is a real nice flour to work with, similar in feel to Caputo out of Italy. Like Caputo, you need to be careful on hydration (it soaks the water during mixing, so don't go over 60% total liquid including oil as measured by weight of flour).