Actiontec Ethernet Over Coax Adapter Kit for $80 + free shipping
Amazon offers the Actiontec Ethernet Over Coax Adapter Kit, model no. ECB2500CK01, for $79.99 with free shipping. That's the lowest total price we could find by $33. It includes two adapters and uses existing coaxial cables to extend a home network connection.
5 very similar deals were also reported by some other sources: