The fine by itself should be closer to $230. The court's traffic school administrative fee will run you between $49 & $69 (depending on the court). Then you'll have to choose a traffic school from a list given to you by the court, and you'll also have to pay them their fee and I've seen them as low as $15.
In California, it starts out as a "base fine". Then several different amounts normally referred to as "penalties and assessments" are applied (added)regardless of how you proceed with your case. So you're not saving anything by not fighting it, but you're not adding anything if you do!
Well, for future reference, the vehicle code section you were cited for violating specifically states:
22349. (a) Except as provided in Section 22356, no person may drive a vehicle upon a highway at a speed greater than 65 miles per hour.
... As you can see, it mentions nothing with regards to a time period. So it doesn't matter whether you exceeded the posted limit for 2 seconds, OR, exceeded it for a half hour, you are in violation and can be cited.