The least expense option would be to use TurboTax Basic CD/Download to do all four returns. However, Basic only has a simple interview, and most of the time you will be inputting info directly into forms.
Another option would be to use TurboTax Online instead. You can use the free version for the simple returns and then Premier for the more complex one. However, if the person with the complex return has a spouse and they do their returns together, then both will be charged the Premier price, and that will come close to the price of just getting TurboTax Premier CD/Download, which will do 12 returns (with a net income of above $25,000).
