RE: Can i use any 2.4G receiver with my airtronics?
I'm not sure on that. You'll have to wait for someone that's an actual airtronics user to chime in.
Hobby People had the 3-ch receiver that they specifically list as compatible with the MX-3 sport for 60 bucks, but you'd have to pay shipping, etc.
Sort of like printers and ink cartridges. They can afford to almost give away printers (transmitters) to get you to buy more ink (receivers...)