OK I'm in the same boat as you, auto gts want a 6-speed...
Well this guy named Pluto at newcelica.org had his put in for around 3 to 4 grand, while i did some research and found a toyota dealership to do it for 2 grand in NC where I live... Just do some research and if you dont have a lot of mods on your car then just trade it in for a 6-speed cause its a whole lot cheaper and no hassle with a tranny but if your like me then with mods you dont want to go through the hassle to put them on another car then just talk to your local toyota dealer...
I thought about selling my auto sport shifter to someone who got in a wreck and needs a tranny or wants to do the opposite of us and chances are since its a sport shifter we can get a little of our money back to put into our tranny...
(but its just an idea...)