Suggestion needed for a IoT solution

Assuming your 100-200m spaced nodes are not in a built-up urban environment, then suggest this little 433MHz module, which is available from seeedstudio:

http://www.seeedstudio.com/depot/433Mhz-Wireless-Serial-Transceiver-Module-1-Kilometer-p-1733.html?cPath=19_22

It is fairly easy to use as it communicates via UART/TTL (3V-5V) through it's embedded mcu and uses AT commands to set radio configuration options. There are 3 operating modes, one of which is a low power consumption option during TX, and has low power sleep option. Not so sure about the 1km claim, but when I used with a quarter monopole whip antenna, I was able to communicate at the +100m range (not that my tests were in way scientific).

Otherwise maybe look at si4463 transceivers. Suggest searching https://www.tindie.com for some ready made modules.

A lot of nodes in a mesh network sounds like a good application for a Zigbee network - if your nodes have the horsepower to run a Zigbee stack.

I have used the TI Sub 1GHz and they work very well and are reliable and well supported, you can et a pair from TI / Newark for about 20$ as Booster packs, they come with an MSP430 CPU each as well so not too bad value for the money and you can test out the product

you get 2 Rado boards with an area on them to mount a MSP430 if you want and a little bit of other circuitry

http://www.ti.com/ww/en/RF-BoosterPack/?DCMP=iotenergia&HQS=ep-mcu-lpad-maker-iotenergia-lydeseign-lp4-en

and a project I did last year with them

http://www.element14.com/community/community/designcenter/ti_launchpad/blog/2014/07/24/the-electronic-referee-wireless-915mhz-5-nodes-5-different-launchpads