There have been two generations of this vehicle. The first generation, which was in production until 2006, came with an I4 engine standard and a V6 engine optional. The newest generation comes with more powerful engines, but the I4 is still standard.
Both generations of the Tribute have come with 4 speed automatic and 5 speed manual transmissions. The automatic is now the standard item.
No Tribute was made for the 2007 model year. The 2008 models include the base model and a hybrid Tribute that will get much better mileage.
These vehicles have been showing up on the used car market for years now. You can find some good deals on eBay, just look for a clean title and low miles. You can also find some good prices on parts on there.