For transmitter: 1/2 74HC74 D-flop, 1 74HC164 shift register (serial in, parallel out; taps at bits 3 and 7), 1/2 74HC86 XOR. Pushbutton (undebounced, but who cares?), 4.7k 1/8W resistor.
For segregating the two: 0.1uF mylar capacitor, 1/8W resistors, 10k and 15k.
For receiver: 1 74HC164 shift register (serial in, parallel out; taps at signal + 3 bits later + 7 bits later), 1/2 74HC86 XOR. Red LED, 220 1/8W resistor.
Two power supplies (+5V and ground) and two frequency generators.