Quantity   Component name
1 × Arduino Nano Clone Get them from Aliexpress for $1.90/each
1 × nRF24L01+ -OR- Si24R1 Chinese clones are Si24R1. They don't play nice due to preamble errors
1 × Sensors Really, whatever sensors you need for your project
1 × Actuators Buy, scrounge, and dig up whatever motors, solenoids, steppers, or what you need