This is what my 433 MHz accesspoint (well actually its a router) looks like:
It consists of an AVR NetIO Board i bought from Pollin.de plus the RFM12 433 MHz transceiver. Its firmware is based on Ethersex. All communication is currently done using TCP/IP. The sensor boards run a minmal webserver, from where the sensor information gets polled regularly. After some ugly bugs where fixed recently and after i added some capictors to stabilize the ENJ28J60 ethernet IC, it runs stable since a week or so.