Help with building a RC transmitter and receiver

Hi, I am trying to build an RC spy vehicle, however instead of using a normal bulky RC transmitter I would like to build a small one myself. It needs to have 4 channels and work at least 100 meters in an urban area being able to penetrate walls, the further the range the better. Could someone recommend a transmitter and receiver I could use that would fit this purpose and could anyone tell me how I can convert it into a typical RC signal that would be accepted by my motor controller? I am relatively new to this stuff so any help would be appreciated