I purchased a "Certified" '06 Sport on a lease return last year. I strongly recommend the Sport for a number of reasons, mostly for the X-reas suspension and the additional features it comes with in comparison to the SR5.
One caveat, and this may be more suitable for a thread of its own, when purchasing "Certified" this only means that the dealer has only gone through the safety features of the truck, such as lights, brakes, fluids and tires. What is confusing is that they will change the oil, but not any of the other necessary changes such as plugs, differential and transfer case fluids, so it is important to ask for a maintenance schedule and compare it to the mileage. I would negotiate that this service be completed if it wasn't done at the proper mileage interval.
This, however, is what is valuable about purchasing it from a dealer. They have the ability to look up service records right there.
Here in Salt Lake, 4Runners and Tacomas are a hot commodity and the lease return is a good buy for someone that didn't elect to buy it outright.
Good luck and I'm certain you'll be pleased!