Wireless door sensor needed

[clemslay@xxxxxxxxx]

I need to monitor a door of its use.

I am thinking of a reed switch & magnet on the door,
connected to a RF transmitter with a receiver ~50 feet
away, after that maybe record use somehow,
or turn on a latching circuit to tell me that the door was
used "today".

If it would be X10 through the power line (can do),
I would surely want to give it its own house code.

Any ideas what would work best, and at a low cost?

Thanks!