List_TransmitterReceiverModules

China || Hong Kong

(takes a couple of days to deliver but is really cheap)

• http://www.seeedstudio.com/depot/index.php?main_page=product_reviews_info&cPath=139_140&products_id=127
• eBay: search for "Arduino 433" or "RF Link kit"

Germany

• http://www.watterott.com/de/RF-Link-2400bps-Empfaenger-434MHz
• http://www.watterott.com/de/RF-Link-Sender-434MHz
• http://www.conrad.de/ce/de/product/130428

UK

• http://www.quasaruk.co.uk/acatalog/Radio_Modules.html