Saleward-US via Amazon offers the Homful 4-Port Gamecube Controller USB Adapter for $19.99. Coupon code "8C85SCQE" smashes that to $13.99. With free shipping for Prime members, that's the lowest price we could find by $35. It features support for the Wii U, Nintendo Switch (requires firmware 4.0+), and PC. Deal ends February 28.