Replied to your PM tkbyd, unable to PM rcrowley.
Folks seem interested in several things that are possible to cram into a 555 and a quad NAND. I have whupped up a Dumb Dirt Cheeeep Wireless (DDCW) circuit that can be configured for several modes :
One or Two button remote :
One or Two channel alarm contact :
Single or Dual channel environment sensor :
Dedicated precise humidity sensor :
Single channel "battery saver" sensor :
Dynamic data range compression for one or two channels :
Dumb "programming" is done with 7 trace cuts and/or 5 pull up resistors.
Included a linear voltage regulator (for high accuracy) but it could be jumpered out (to save battery) and still have a single common PCB for all DDCW configurations. This would fit on a coupla square inches of PCB, run off a 9v battery, or anything between 7 and 12 v and provides power and data to an RF Transmitter module that could plug or solder right on the end.
A board like that might sell for $25 in prototype quantity, BYO transmitter. Naked PCBs get awful cheep in quantity, thats where everyone benefits by having a common PCB that supports many configurations. If they got wildly popular and the community pools purchases of parts and boards the cost could come down by 2/3 or more.