However, not being able to power them from batteries for extended periods of time is a big drawback on some other projects. Digi's XBee modules (http://www.digi.com/lp/xbee/) seem quite interesting, but they are quite expensive. There are Ciseco's RFu - 328/SRF modules (https://www.wirelessthings.net/rf-328-a ... er-rfu-328) too, but even those are not cheap enough for what I have in mind.
On the other hand, I have also being toying with the idea of pairing Arduino Nano boards with some random 433MHz module, but I am not very confident on the reliability of that setup.
Does anybody have more ideas? Many thanks!