CAN V MAKE ?DETECTOR TO DETECT RFID TAGS

Dear Friends

In my case, I want something like this ( I am  a non technical person in field of electronics )

I need a small instrument( can be a PDA or any small device)  which can detect RFID tags( fixed on various locations, walls, door, window etc) and read its data (few English lines)  stored in RFID tags.

Is there a kit available or a method to devise such application. If you can please send me such products information with URL and approx. cost?

I read the Chapter No. 8 tracking employees. Can we with the same concept design something by which we can detect Tags which are located at various parts of the building? Your advice will provide me clear direction to go about!

Your help will be appreciated