Design & implement a prototype of RF based Wireless Mail box Alert Alarm & Indicator

Hi All, Thanks for your interest in Wireless Electronics. What I am looking for is something similar to MailChime. You can find more info on MailChime at http://www.amazon.com/Mail-Chime-Wireless-Alert-System/dp/B00103FDDU/ref=cm_cr_pr_product_top What is Mail box Alert Alarm? Mail box alert alarm is an electronic gadget that will alert the resident at home when there is a letter/post in their mailbox. Requirements- 1. The sensor needs to be able to detect letter/post in all kinds of mailboxes including vertical, horizontal and sentinel type mailboxes 2. The Sensor needs to be battery power supplied and the battery power usage has to be minimal so that the batteries will last longer 3. The Sensor needs to send a wireless signal via RF, when there is a letter/post in the mailbox 4. The Receiver needs to be compact and be able to receive the wireless signal sent by the transmitter and beep an alarm & make visual indication such as glowing a LED. 5. The receiver needs to have a reset button for the user to reset when they needs to. Say, after picking the mail 6. The receiver needs to be battery supplied so that the user can take anywhere within the house 7. The range of operation needs to be atleast 100ft to 200 ft 8. The transmitter power needs to adhere to Australian ACMA standards. Say, if using 433 Mhz, then the transmitted power needs to be less than 25mW 9. The interference needs to be zero in general. In particular, if there are two devices used by two neighbours next door, there has to be zero interference 10. Finally, the design has to be the cheapest to save cost but it has to be high quality product Please email for any enquiries. I am expecting this project to be done in 2 weeks time thanks Ram Jothi