Avoid Harbor Blvd - it's expensive. There are 2 on Euclid that are really cheap, a Chevron at Euclid and Katella and a Shell at Euclid and Chapman. From there you can keep on Euclid going south and hop on the 22fwy West which turns into the 405 North and runs smack into LAX. Euclid runs parallel to Harbour, a couple of short blocks West of Harbour.