For a limited time, you can buy the PowerA Wired Controller for Nintendo Switch GameCube Style for only $6.99 (72% off). Get FREE Super Saver shipping on orders of $25 or more (or with Amazon Prime). This is the lowest price this controller has been listed on Amazon (and the lowest price I've seen anywhere).
If you prefer wireless, you can buy the wireless version in grey from Amazon for only $17.49 (65% off)
GameCube style controllers are widely considered the preferred way to play Super Smash Bros. Ultimate. Pull off precise attacks using octagonal gated sticks, larger A button, and nostalgic muscle memory on this officially licensed wired controller for Nintendo Switch. The original GameCube design has been improved with larger shoulder buttons and D-pad, plus added left shoulder and system buttons for compatibility across all Nintendo Switch games.
Be sure to check out all the Amazon deals that I've been posting for some great deals
Please note: Amazon prices tend to change quickly, so be sure to check the price before you buy.