It might make economic sense if just one model is involved to look for a complete TX/RX combo. The HobbyKing 4 and 6 channel outfits are available at a cost lower than many companies receiver only deals. They are re-badged Flysky, and the expectation with an established company is that they will carry on in business. At the bottom end of the market, it is not uncommon for any particular line to stop being available. Sadly, there is very little compatibility with 2G4 radios at the basic end of the market.
I've recently had the problem of replacing a bottom-of-the-market transmitter. Worked OK with the supplied receiver, but wouldn't bind with the earlier (identically numbered) receivers.