You can log out at any time and your information is automatically saved in TurboTax Online. Just be sure to log back in using the same username and password.
Your final pricing will depend on what "level" or edition you end up having to use. That depends on your individual tax situation. And there are other features and options that you may or may not wish to utilize, all with different pricing.
Maybe the info below will help you determine what edition you'll need:
https://ttlc.intuit.com/replies/3300068
You can view the current prices by going to the TurboTax website, linked below.
https://turbotax.intuit.com/
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***