1999 GMC Sierra transmission wont shift

1999 GMC Sierra mileage: 150,000. After getting off thruway from a fast acceleration, I noticed as I turned onto a 30 mph street that the engine just started to rev high after leaving a stop sign, almost like the truck was in neutral. I stopped fully and proceeded forward, I noticed that it would go into first (auto transmission) and it would not go into second (just rev high as I accelerated) and it would not drop back down into first. I was able to coast home. I checked and added fluid low, about a quart and I test-drove it again and still the same problem. It seems to be a transmission problem. If so approximately how much (new, refurbish rebuilt), what type of transmission. Basically, what is the best way to go from here?