Starting this year 2019 TurboTax requires a valid license key in order to use.
Only well-known reputable authorized resellers like Amazon, Staples, Office Depot, Newegg, Costco, etc. can sell TurboTax downloads.
Prices for Deluxe also depend on whether it has a state program included or not. Current prices on Amazon, for instance, for the 2019 Deluxe are:
29.88 (Deluxe without state)
39.86 (Deluxe with state).