I have been using Turbo Tax (online) since 2001 (tax year 2000). Using the federal version only most of the time.
Some of the places I found they offer discount code, in addition to the discounts on the official websites. It seems this year (2017, for tax year 2016) their online prices has some discount, and we can combine with affiliated links from other websites. For examples, they lowered the deluxe from $54.99 to $34.99*, and premier from $79.99 to $54.99*. The discounts from discover ($15) knocks the premier down to $39.99.
1) Discover Deals (discover card)
3) Southwest air (points)
Related: last year’s post here.
(Update 03-06-2017) Last but not least, there is a free tax form here, please note this is NOT Turbo Tax.