I want to file three different returns. Am I going to have to purchase Turotax three different times?

If you use the online version, you will pay for each individual return you file. With the online version, you can only file one return per account. Period. But you can create up to 5 accounts per e-mail address.

YOu will pay for each federal return you file, weather you print and file, or e-file.
You will pay for each state return you file, weather you print and file, or e-file.

With the desktop version, you pay for the CD only "ONE TIME" and physically install the program on your computer. With that version, you can file as many federal returns as you like. But per IRS rules, you can only e-file 5 of those federal returns. After that, you have to print, sign and mail the federal returns to the IRS. You'll only pay for the stamp on the envelope.

For state taxes, you have to purchase the state program for each state you want to file. You pay for the state program once, and that's it. You can then prepare as many returns as desired for that specific state.
To e-file the state return you pay *again* for each one you e-file. However, if you elect to print, sign and mail the state return, that will cost you nothing extra beyond the postage stamp.

You can buy the desktop version of the program on CD in numerous stores. Or you can purchase it directly from TurboTax at https://turbotax.intuit.com/personal-taxes/cd-download/  When you buy it online, you can download the installation and install it on your computer immediately. If you also want a CD mailed to you, then make sure you indicate you want BOTH download and CD. Otherwise, you will NOT receive a CD.

You want to buy the version for the most complex return you will file. For example, if one of your returns will require a SCH C for self-employment income, then you want to purchase Deluxe or higher.