Mini VGA/Audio Cat 5 Extender max 150m, ATEN VE022
300m CAT5e/6 S-Video + Stereo Audio Extender - from LINDY UK
Amazon.com: Analog Audio Extender RCA 3.5mm Stereo Over Ethernet Single Cat5e/6/7 Cable up to 1475 Ft (450m) Converter Adapter Support PCM Stereo POC(Power on Cat) : Electronics