The relationship between price and cost only becomes causal in a fully commoditised market where margins have been driven down to razor thin levels by competition. That is clearly not yet the case for RC radios. For the moment, brand status and superior quality continues to support the high margins enjoyed by the traditional manufacturers. As the challenge from Chinese brands builds steam, prices will continue to fall. Whether this is good or bad depends on your view of the merits of having global diversity in brands and the value of all the advertising and sponsorship provided by the major brands as we know them today.
Certainly it is already possible to buy a high-function 9ch Tx for $80, a high performance 8ch 2.4Ghz tx-module/rx combo (with telemetry) for $55 and additional 8ch rx for $28. There are already two separate open-source projects under way creating powerful and novel feature sets that in time will rival or exceed, at least for some, the value of those from J/F/A/H/S.
It is a fascinating time to be in the hobby