Several radio manufacturers make Airtronics compatible receivers (Hitec, FMA, etc...), and you can use any brand of servo, just make sure the plugs match.

http://www2.towerhobbies.com/cgi-bin...?&I=LXN536&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXN524&P=0
http://www2.towerhobbies.com/cgi-bin...?&I=LXCXM9&P=0
http://www.servocity.com/ServoCity/P...receivers.html

https://www.fmadirect.com/site/Detai...1000&section=1

Keep in mind that, in North America, Airtronics uses "positive shift", while Futaba & everyone else uses "negative shift". Therefore, you have to make sure theat if you buy an "off brand" flight pack, it is compatible with your Airtronics transmitter.