If you were to use Online TurboTax, you may not save much money. You might not be able to use Free Edition because of the new tax law, which for some people requires one of the new Schedules 1-6. So more people have to upgrade to Deluxe than previously.
If you try to use Free Edition and have to upgrade, then Online Deluxe is currently 59.99, and a state return is 44.99. So if you have both, that would be 104.98 plus possible sales tax.
Desktop Deluxe is 79.99 when purchased as a download directly from TurboTax, and includes both Federal and State programs.
You might be able to find it cheaper at a reputable authorized retailer such as Amazon, Staples, Office Depot, Newegg. But be aware that Deluxe comes in 2 versions--one that is Federal and State combo, and one that is Federal-only. So you have to be careful as to which version of Deluxe you are buying.
Whatever you do, do NOT do an Internet search and choose the cheapest deal. The "too good to be true" deals are usually scam sites with pirated software, and could install malware, steal personal info, etc. Very few retailers are authorized to sell TurboTax downloads, and they are big well-known ones as I indicated above.
