What do you need to do in RF? What range? How many devices are you going to
use?
Here is my "bakc of the napkin" calculations for 2.4GHz radio components in low volumes --
Transmit/Receive Radio Parts + PCB $2-$3
T/R Radio + Zigbee $8-$10
Integrated Solution (XBee) $20
On my not-quite-ready list is this radio PCB -- http://tinyurl.com/yl53nju
This would be the $2-$3 in parts solution. 1 QFN and a bunch of 0402s.
Unfortunately the length of the not-quite-ready list gets longer each day 
(* jcl *)
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