RFID help

I'm trying to make something so that once i enter the room it know its me and turn on the lights and does various things. i was thinking of bluetooth but thats too expensive. I don't really have much of a budget, so i turned to RFID but that has limited range. i was wondering if there are any other alternatives to these methods for person detection that aren't expensive.

There are passive infrared sensors that can tell when anyone has entered an area. They are relatively cheap. They can't distinguish you from anyone else, though.

I am looking for something like this too. One thing that you can do is to detect if someone went inside or outside the room. You place a laser emmiter on one end of the doorframe, and a LDR on the other end. Of course you have to have two of them:

x.........................................................o ............................................................ x.........................................................o

x = laser emitter o = LDR (Light Dependant Resistor)

With this you can figure out if someone walked in or out (simply by knowing which sensor was activated first). It tryed it with IR (and failed) - the reason being IR.

The PIR (passive infrared) sensors are good if you want to detect movement but they are not good for detecting if someone (or how many) people are in the room.

But I actualy want to have the data who is in the room also. And I can't find a way to detect that with cheap electrnonics. So if anyone has an idea - I am realy interested.

People told me to use HF/UHF RFID but that seems to expensive for what im looking for.