“Shop locally.” I certainly agree with this principle and follow it as much as I can. But, there is a limit. In Grass Valley I filled up my car with gas at $4.69 a gallon on Saturday. Today I drove through Auburn where I saw gas priced at $4.33 and $4.37/gallon. I’m sorry, but with that much of a gap in pricing, it’s worth driving to Auburn. Carolyn Lashbrook Penn Valley …