I know I may be a few days late for you, but here is the deal.
The ticket would have really cost you $685, and now it will only cost you $385 in fines. It was always $300 for the speed, $80 surcharge, and $300 state fee.
Now if you plead it down to 3 points, you will only have to pay $385. You never took the court surcharge into account.
Getting the speed does to 3 points is half, is not a bad reduction for representing yourself. You could have hired a attorney to get it reduced to no points, but that really depends on the area you got the ticket. Some Courts will offer you as little as a 2 point reduction, some courts will offer no reduction, and some courts will dismiss it for $150 "application fee" or a more expensive parking ticket. Which Court was this ticket assigned to?
One dirty little secret is that when you plead to a moving violation, the state collects the whole fine except for the surcharge. When you plead guilty to a non moving violation like a parking ticket which does not go on your license, the town/village gets the whole fee.