Avlynn - I know you're looking for homemade pizza sauces, but just wanted to mention that I frequently buy Ragu's jarred "Pizza Sauce". It's thicker than regular jarred pasta sauce, & with a little extra crushed red pepper flakes is absolutely delicious & truly makes a homemade pizza quick & easy.
As far as a "white pizza sauce" - white pizzas really don't have a "sauce" per se. In fact, the only white pizza I've had that actually had a sauce was one made with a mixture of Ranch dressing & Romano cheese. Most white pizzas consist of a garlicy cheese combo rather than an actual sauce.