the 3 channel trainers are normally electric parkflyers. this is how i started and i learned on my own-trial and crash,uh i mean error. its a matter of personal preference. first you need a radio-get a good beginner 6 channel computer radio-it will work with any plane you get unless its a helicopter or a very complex plane. i suggest the futaba 6 exa. ok you have a radio. now you need to choose a trainer plane
-electrics are fine but if you want more quality, power, and flight time, they can get more expensive than a basic glow plane. parkflyers with 10 dollar motors are also a blast. the new, more expensive electric motors get up to 300 dollars and can power big glow planes. if you like quiet and clean, go with electrics to start and go to hobby-lobby.com-they have a wide arrangement of trainers, sport, ducted fan, scale, etc. planes. they also tell what you will need for each plane to complete it.

-many people suggest going with a 4 channel glow trainer plane-these are great if you like a lot of different and exciting planes. the noise and large size of these planes makes it fun to take off, fly and land, at the expense of noise and engine exhaust grime building up around all your plane stuff. its not too bad. i have gone from electrics to glow because noise and dirt doesnt matter for me. the electric planes of the same capabilities can be up to 2x more expensive.

each plane will require its own engine,radio(transmitter,receiver,servos, and battery), and support equipment(tools, building and fixing supplies, etc.)

if you like electrics get the mini piper or wingo fron hobby lobby. they are easy to fly and build, and repairing a broken wing takes 5 minutes-mini piper is about $250 basic+misc items=$300

if you like glow planes get a sig( i think) kadet lt-40 or lt-60. i think its the slowest one out there. the nexstar and other trainers are also great. a basic package(brand new) will run about $350, plus accessories, plus tax, plus more accessories=$400-$450

the way i reccomend it (with a 6 channel computer radio) is a little more expensive but definitely worth it-you can use the same transmitter for several planes thanks to the memory chip in the transmitter that stores the plane's settings

also, second hand planes can go down to half the price of a new one

2 keys to success
1.read read read magazines, RCU, etc.
2.get an rc flight simulator, if it doesnt teach you how to fly, it will at least teach you the basics-turning in the air going different directions, setting up a landing, etc. this is very useful

i think i covered most of the stuff. hope this helps. have fun!!