Developing a new System... confused between RFID or NFC.. just a few questions
RFID certainly is cheaper and simpler. 

The main difference between the two is that with RFID the person carries a card/tag/etc. that can be thought as "passive". It is only powered when near (and by) the receiving antenna. NFC is to be embedded in cellphones and uses its source of power (the battery).

RFID is pretty secure for most applications. It is widely used around the world for bus fares. Only when you have applications that require more security (credit/debit card transactions, for instance, in which the average transaction amount is significantly higher) it wouldn't be recommended. Thus enters NFC.

For a test/demo environment, I'd recommend you to visit SparkFun or Adafruit. Their products are aimed at the hobby market, so they are pretty easy to start using. In general they'll open a virtual serial port via USB, so what you'll need in PHP is just any standard library for sending/receiving data through a serial port.