I did a search on this last month, and I found that transportation is provided by maingate transportation, and I think it is like $ 10 per person (don´t remember if one way or round trip).
We just stayed at Windsor Hills, and on the days dh had to leave the parks early at 9:30 to go back to the rental to do some remote online work, he would take the Disney transportation bus to the Animal Kingdom, and then a taxi using the Sherbeth Road shortcut, and it was only $ 8.
So I guess you could do it backwards, a taxi to Animal Kingdom and Disney transportation from that point.
HTH
Julie