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RF (Radio Frequency) devices are very expensive to start out with. In order to legally use and sell them, they must go through a series of FCC "type-testing" which takes a lot of time and money. Everything sold in this country that radiates radio frequencies must be type-tested. I'd say that it would cost between $10,000 and $25,000 by the time you got something ready for sale.
The only real drawback to infrared is the line-of-sight requirement. In general it would also be cheaper than RF. Based on price, you should also be able to get better bandwidth, or speed, using infrared. This would be important if you are trying to send the analog data you mentioned.
Whether using RF or infrared, most standard communication protocols will easily let you work with 8 to 32 remote devices into a single receiver-transmitter. Each remote would have a transmitter and receiver, as would the "base station" (or whatever you might want to call it).
Generally they are referred to as master and slave devices. The slaves ask to be acknowledged and when the master gives permisssion, the slaves send their data, along with some type of verification code. The master then compares the data with the verification code. If they agree, the master accepts the data and processes it. If the master misses part of the transmission from the slave, it asks the slave to resend the data. Even a slow system can process thousands of these transfers per second.
There are various protocols that determine in what order the slaves can be acknowledged. You can use "polling" where each slave is polled every few thousands or millionths of a second, or a slave can set a "flag" Once the flag is set, the master knows that a slave is waiting to talk. There are also interrupt driven systems, where certain slaves, or certain types of communication take precedence over other slaves. If their priority is high enough, they can "interrupt" whatever else is going on. Because of the speed of the communication (with infrared, generally several million cycles per second), the masters and slaves are mostly in an idle state.
You need to find a friend who is into microprocessors.