A4C via eBay offers the 5-Foot 3.5mm Male-to-Male Auxiliary Cable 2-Pack in seven colors for $2.33. Add two to your cart and the price for all four cables falls to $2.78. With free shipping, that's 70 cents per cable, tied with our October mention, and $8 below the lowest total price we could find for four of these cables elsewhere. (We've seen 3.5mm cables for less, but not with angled connectors or flat cables.) They're compatible with any audio device with a 3.5mm stereo jack.