California has the cheapest traffic school courses in America and the most misleading sticker prices, because the course is the smallest number on the bill.
Three pieces. First, the fine, and you pay all of it. Traffic school in California doesn't reduce or dismiss the ticket, it masks the conviction from insurers. A typical 10-over ticket runs $234 with assessments. Second, the court's administrative fee for the traffic school option, typically $52 to $55 depending on the county. That fee usually costs more than the course. Third, tuition, and here the market has raced to the bottom in your favor: among schools we track, 5DollarTrafficSchool is genuinely five dollars and has been since 1998, Improv runs $24.95, Aceable $29. All of them cover the same 8-hour DMV minimum, because the state sets the curriculum floor, not the school.
So the honest arithmetic on a typical ticket: $234 fine, call it $54 to the court, $5 to $29 for the course. Roughly $300 all-in, of which the part you get to shop is under thirty bucks.
Which raises the fair question of whether $300 is worth it. Our California data says it isn't close. The three-year insurance exposure on that same 10-over conviction is roughly $5,385 as a ceiling estimate, because California insurers price visible convictions hard. Masking keeps the conviction confidential from them under Vehicle Code 1808.7. You're spending about $85 above the fine you owed anyway to take a four-figure risk off the table.
One warning on the cheap end. A $5 sticker sometimes grows fees at checkout, so read the final total before you pay. The schools we list on the California page are compared on the checkout price, not the banner.