Also, toll booth fares are not negotiable--they vary depending on whether you drive a car, bus or truck and the size of the latter two.
And "acting poor" in Mexico is incredibly tacky. If you are vacationing there, you surely have more money than 90% of the population. Lighten up.
I drove this about 7 years ago, I can't remember the distance, and we stopped a lot, so I'm not sure on the time either. But the tolls were not much, about a dollar or two. There was 2 or 3 tolls booths along the route. And I'm pretty sure it was different for different people. I think they charged us more because we were American. FYI act poor everywhere you go, most things are negotiable and if they think you have money, or they see money in your wallet, they will use this to their advantage. Also on that drive I was warned by the locals not to flash cash at the booths because of carjacking/robberies on the road. Its a beautiful drive though, good luck, and have a great trip!