This is the culmination of work by many people all working towards making it easier to use the cheap nRF24L01(+) modules. This particular repo contains Arduino, RPi C++ and RPi Python implementations for versatility.
Please refer to individual folders for more information. Guides for possible usage of these modules can be found on my website, http://www.jonathongrigg.com
I have had great success buying off eBay, where modules with PCB antennas can be had for around $1.50 each!
More powerful modules with external antennas can be had for ~$10 also on eBay