Nice video from defcon (yeah I know that was 3 months ago) on how to reader RFID cards, or prox cards from a meter away. The author basically hacks a long range HID reader and hacks into it. The readers are running 200-400 bucks on ebay. Oh and it all uses an arduino.
http://www.bishopfox.com/resources/tools/rfid-hacking/attack-tools/
http://dangerousprototypes.com/2013/10/08/defcon-video-live-free-or-rfid-hard/