Today only, until 8:39 pm ET, Amazon offers Prime members the Actiontec Powerline Ethernet Adapter Kit, model no. PWR511K01, for $19.99 with free shipping. (Non-members can spend $35 or more for free shipping; otherwise it adds $8.54.) That's the lowest total price we could find by $20. These adapters plug into wall power outlets to expand your home network without running Ethernet cables through the walls. It provides up to 500Mbps data transfer rates.