This is an old post, but since it's been re-awakened, I'd like to add to it. The hardware options for RFID are about the same now as back then. One thing that wasn't mentioned, however, is that there are several different radio frequencies that RFID operates on. They stretch all the way from VLF radio (125 kHz) to microwaves. So you would want to make sure that your tags and readers are compatible.
The other item
you should consider is range. Some RFID is extremely short range, other RFID is capable of reading a meter or more from tag to sensor.
And finally, some RFID is passive - such as the little "postage stamp" thingies you often find in product packaging, and some is active - where the tag has its own power supply and transmitter. Those are typically for longer-range use.
While technically not literal RFID, the Applie iBeacon for Bluetooth also acts like an active RFID "tag".
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.