I want to build a temperature control network over my house reading data from each room and sending it to the main board for further processing. I need about 6 sensor nodes sending the data over the air to the main node. There are tons of tutorials of making master-slave temperature/pressure etc control systems of 2 Arduino boards communicating via wireless channel. I find it a bit expensive to have a board per sensor node. Is that possible to build a sensor device without a controller using just a sensor, a battery and a wireless transmitter plus required radio components? It's ok to send raw data to the main node. Assuming it knows the protocol it will be able to decode the data there from all the incoming channels.
@Sergey if its cost what's bothering you , there are numerous low-cost options for MCUs. For eg you can club a MSP 430 ( probably <1$) chip with a cheap RF transmitter which wont burn a hole in your pocket and is absolutely reliable. Wifi modules can be a little expensive and need constant connectivity. So, you have a choice on this.