Just found this post https://www.hackster.io/Talk2/temp-and-humidity-sensor-with-a-cr2032-for-over-1-year-580114 showing some details about using a CR2032 to power a sensor node. By my calculations, if the author removed the LED at all the solution would last for over 2 years!
@jfeger hey... I don't have it in this computer, I sort of moved away from it and I'm using my own "protocol" and code. but i'll try to find the working mysensor sketches on the company's laptop and post here. From the top of my head I don't remember changing anything apart from the RFM69 config parameters documented for the "mysensors".
@gohan it worth for me... I thought the same initially, but after lots of time spending building my own nodes, which were never 100% and some quick maths I believe it's a good board for low power nodes.
RFM69: $4; Arduino Mini Pro: $2.5 - $3; Step-up Regulator: $3.5; 4Mbit Flash: $2 - $3; SMA 2dBi Whip Antenna: $5 - $8; SMA Connector + LEDs + Buttons: $3 - $4; PCB Headers + Passives: $1.5... Total $21.5+?!
That's what the board comes with (I assume). I must say that I would never build my node with all of the components, for me I prefer to focus on my project instead of build nodes from a Mini Pro, soldering the step-up and the RFM69 and testing everything... plus the whole thing look like a Frankenstein 
There is a TI paper about adding a big capacitor in series with the coin-cell battery to minimize the voltage drop during high-current peaks: http://www.ti.com/lit/wp/swra349/swra349.pdf, also another interesting article related to low-power and CR2032: http://www.low-powerdesign.com/121312-article-extending-battery-life.htm