IR cable

A friend of mine needs to buy a 30' IR cable. She wants to have the AV components at the back of the room and doesn't want to have to turn around every time she wants to change the channel, so she will have an IR sensor at the front of the room, and the cable will run back to the equipment (sorry if I'm stating the obvious).

The local high end AV store quoted her $900. Is this reasonable? My jaw almost broke the glass counter, it dropped so fast.

Also, where is there a good guide to HDMI cable and cabling in general? i.e. what's needed for high quality, brands, and reasonable prices. I know one way vendors "get" you is buy selling ridiculously expensive and unnecessary cable.

Any guidance greatly appreciated, and thanks in advance.