Quickest, Cheapest U.S. Teacher's Credential

So I’m back in the U.S. doing this postdoc. Due to the academic job market (and my missing Taiwan) thinking of a ‘plan B.’ I know having a teacher’s credential will increase my job options in Taiwan (esl ain’t so bad). Wondering if anyone has any info on the fastest and cheapest way to get a teacher’s credential here. I’m in California btw.

Thanks!