Around here $15 to $17 for “a plate of spaghetti” is about what you’d expect, especially if it’s, say, linguini with seafood…. even more in San Francisco.
“Spaghetti and meatballs” is considered rather American, and is served in pizza places and old-fashioned family style restaurants, sometimes as a starter…but still costs at least 10 or $12.
California is expensive!
Which is why I don’t get out much.