I am not sure I would go with a 310 or Aztec for training. High maintenance costs, fuel burn, and insurance go along with those two aircraft. I did a lot of research when looking at which aircraft I wanted my flight school to operate. It came down to the Twin Comanche, Seminole, and Duchess. There happens to be a lot more Twinkies out there to choose from.
It if you are not looking to use the aircraft for charter as well as training, it will be tough to make this airplane profitable. Especially hard if you have another flight school in the area with a Seminole. They will be able to under cut you big time.
I hate the seminole, but it is relatively cheap to operate.
but to answer your question.
My buddy's flight school had an Aztec on the line, it was $215/hour wet (which is an amazing deal). This was the price as of march 2008, as gas went up, it was scheduled to raise in price five dollars every month to off set fuel costs.
The airplane was based in the midwest (extremely cheap flying). i.e. my flight school has a seminole for 230/hour wet. There is a baron in the neighborhood for 300/hour wet.
The aztec is going to fly the rest of the 100 hour off then go for scrap.
It is done dealing.
It is hard to make money with them if you are looking for only training.