Amazon offers Prime members the Unitek USB C to USB 3.0 Mini Adapter, model no. Y-A025CGY, for $8.99. Coupon code "DCMFNB3B" cuts it to $4.49. With free shipping, that's the lowest price we could find by $3. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $8.02.) It features a data transfer speed up to 5Gbp/s.