Alternatives to X10 devices

[BoyntonStu]

As I continue developing  the www.Water-On-demand.us project I understand that X10 is not a reliable supplier of components.

The control system is simple:  Turn off a 24 VAC water solenoid valve when a water leak detector closes a dry switch.

A wireless signal must reach a receiver located in the garage from various locations anywhere within the house.

BTW The system requires one receiver/switch and multiple sensor transmitters. 

Sellers offer multiple receivers packaged with a single transmitter.

I have asked, but they are unwilling or unable to sell separate transmitters.

I am presently using the X10 PSC01 interface.

Battery powered units is not an option.

It seems that rf transmitter/receivers is my best and most economical solution.

Any ideas?