Which receiver you need will be dictated by the radio you have. There’s plenty of sub $20 options in common protocols, look at radios if you haven’t already. You don’t need an expensive TX from a big brand to fly.
You can build a glider, the Simple Soarer or Tiny Trainer can be built without servos, or you can centre the servos, set them up inside, then finish the plane, add a nose weight to balance it, go chuck gliding, then add a radio later.
I bought my gear in stages, lots of it second hand. A simple Flysky FSi6 radio will fly anything FT for under $50 new. They come with a receiver. Servo tool is under $10 if you want to get building and cheap 5 or 9g servos are about $3 each.