rfid projects

i want to build an access control mechanism for cars as a project

i want to connect an rfid receiver to a micro an based on the signal it receives from a tag about 5m away , the micro shd send a signal to some motors to raise some bar for the car to pass

now how can i get the rfid receivers and tags because i don't want to build the receiver from scratch as i have seen on the net

can i buy the receiver and the tag and just incorporate in my design

if u have done it before how did u get the receiver and tag?

i mean from where did u buy them