I received a 1099 Misc for 2017 which was not included in my 2017 tax return. What do I need to do in order declare this income and what is the cost with turbotax?

Here's a partial answer.  To learn how to file an amended return for 2017, click this link: https://ttlc.intuit.com/questions/4252204-how-do-i-amend-my-2017-turbotax-online-return  or if you have a Turbo Tax CD - this one: https://ttlc.intuit.com/questions/4251801-how-do-i-amend-my-2017-return-in-the-turbotax-cd-download-software 

I don't know if there is a charge to e-file.  Probably free for Fed, with a charge for state.  But if you don't want to pay an e-filing charge, print the amended return(s) and mail, using snail mail. You can always begin the e-file process and then back-out if you see a fee that you don't want to pay.