Does anyone know how long a tarantula can live?

A female tarantula can live 15-25 years! Or according to wikipedia "female specimens have been known to reach 30-40 years, and have survived on water alone for up to 2 years." Isn't that gross?! Jonathan is determined that he wants to have one as a pet. The really crazy part is that we are considering it. Evidently they are popular pets (who knew?!). Jonathan is really fixated on getting a tarantula and talks about it everyday and is even willing to work really hard to save the money for one. He already catches spiders and keeps them as pets in a mason jar (wait let me clarify--I as an awesome mom catch the spiders much to my disgust). Tarantulas eat live crickets and occasionally when mature a live mouse (yuck!). I do not like mice--in fact I would rather have a pet spider than a pet rodent. Jonny tried to sell me on the fact that if we had a mouse in our house we could get our pet tarantula to go after it. I think if we get a tarantula I will have to have some legal document drafted saying that I wouldn't have to touch it or take care of it (unlike the fish that I said I didn't want to get because I didn't want to be in charge of cleaning the tank...but of course it is up to me to clean). I still am not sure what we will do but Jonny is so excited about it that it is making this a tough decision--fear of big spiders vs. my little boys dream. Hummmm....