The whole game is $14.99
Phoenix Wright: Ace Attorney - Dual Destinies is out this week on iOS, and it's basically a port of the 3DS game with an enhanced graphical filter. You can nab the first case for free, buy each case piecemeal for $4.99, or buy the whole package for $14.99.
For reference, the only other version of the game is on the 3DS eShop for $29.99. If you've been holding out because you didn't want to pay $30 for a digital game back when it hit the 3DS, wait for the inevitable iOS sale and take the plunge.