need ideas for a short range singleplex transmitter project

I need to build a fairly simple one way transmitter/receiver (one receiver mounted, and up to 3 hand held small transmitters) Basically there will be a base unit box with a light and possible buzzer and several hand held push button transmitters that need to be able to set off the light/buzzer on the base unit when the button is pushed. effective range would be around 150 feet or less. I need any of the hand held transmitters to be able to set off the base unit regardless if 1,2,3 or all of them are activated at the same time. The base unit needs to reset to off after a few seconds after being tripped.

I have what I would call intermediate knowledge of electronics but I learn pretty well I think. What I really need are some ideas or places to look for some parts to start building some prototypes.

anyone?

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Also what type of wireless signal would be good? I need something that wont be susceptible to interfrence?