For your money, you wont' get any better deal on Korean-style noodles than here at Zazang. You can easily get out of here for less than $6 per person, including tax/tip.
They have a limited menu (a few types of noodles, potstickers, a few rice plates), so hopefully you come here already knowing what you want.
They never get too crowded (probably b/c of their off-the-beaten path location), and parking is never really an issue on Geary or nearby streets.
Service is a bit slow, but the food is worth waiting. Usually only one cook and one waiter to serve everyone.