I wanted to e-file state & federal returns and it looks like I picked print state return by accident. Would I be able to e-file still and would it cost more money?

You changed your mind, and want to e-file your state tax return instead of printing and mailing. As long as you haven't already mailed your 2018 paper return, you can switch to the e-filing method (through October 15, 2019). Some states now require e-filing their returns, and some federal and state returns must be e-filed together.

For more information see the TurboTax FAQ below:

https://ttlc.intuit.com/replies/5561257