There is a Vietnamse Supermarket called 88 Seafood Market just off the La Sierra exit in Riverside. I went there today. The prices are reasonable. The market is clean, big (used to be an American Supermarket, and the vegetables including mints are fresh. They also have a fresh meat and seafood counter. A good place to shop for VN groceries if you do not want to drive all the way to O.C and stuck in traffic going back or when you are missing a certain ingredient for a dish.
88 Seafood Market
11160 Magnolia Ave
Riverside CA 92505
I agree. Hoa Binh and the 99 Ranch off Chino Ave are the only places I go to. I tried the Korean based Hannam in Rancho Cucamonga, but it didn't do anything for me. There used to be a Vietnamese market in Riverside off La Sierra, but they couldn't last. There is a different seafood market on La Sierra that carries a lot of Asian items, but it is greatly smaller compared to Hoa Binh or 99 Ranch.
Lucky Seafood Ranch Market. 4529 La Sierra Ave Riverside, CA 92505
No matter how much I try to find other places closer, I still find my way to Hoa Binh and 99 Ranch!