Been looking EVERYWHERE for this, as I just got a Wii U a week ago. This is by far the cheapest I've seen this currently, yes it's not as cheap as thegamecollection deal a few months back, but if you didn't have a Wii U/didn't jump on it then, this is still a pretty good alternative imo.
Also, it should be the Deadly Six Edition, which comes with the Nights Into Dreams DLC! :)
When the Deadly Six threaten to destroy his world, Sonic’s new moves and power-ups are the only way to defeat them before it’s too late!
In his latest plot to defeat Sonic and rule the world, Dr. Eggman has harnessed the power of six menacing creatures known as the Deadly Six. However, when the Deadly Six rise up against their new master, Sonic must unite with his arch nemesis Eggman and explore the mystical Lost Hex in order to take them on head-to-head. Use Sonic’s amazing new moves and incredible Color Powers to speed across a variety of unique terrains, racing inside, outside and upside down in every level.
Sonic moves like never before. Vault over obstacles, free run up and along walls, and sky dive between islands at lightning speed. Plus the Spin Dash is back!
Execute new and improved Color Powers. Sonic can now fly through the air, tear up levels and explode into enemies. He’s more powerful than ever!
Speed through a variety of exhilarating levels. Explore massive mind-bending courses, vast underground tunnels and colossal structures in the sky as you run inside, outside and upside down.
Save the world one fight at a time. Take on each of the devious Deadly Six in dynamic boss battles which test all of Sonic’s moves and power-ups.
Race friends in high speed multiplayer races. Take them down across a range of ultra-competitive levels and modes - it’s the ultimate supersonic showdown!