RFID Product design question

I was wondering if anyone knows where i can get a simple RFID circuit. all i need is a read range of about a 6-12 inches, read and respond to one id, and give a relay output. i do not need a computer interface, it would be something similar to the anti theft devices at a store. you pass the tag near the door and the alarm goes off, simple as that

if anyone knows of anything or can design something for me, i will pay, please respond or email me through the forums

thanks alot

Dave