Have a look for RFM98W (434Mhz) or RFM95W (868MHz) on aliexpress/ebay, they're around $14 there. I know in the UK high altitude balloon community they've used

Have a look for RFM98W (434Mhz) or RFM95W (868MHz) on aliexpress/ebay, they're around $14 there. I know in the UK high altitude balloon community they've used them in flights - http://www.daveakerman.com/?p=1850 http://www.daveakerman.com/?p=1850 Although FSK works just as well in the case of balloons.