This is what remains when I took the ELV WS300 PC unit apart – the enclosure:
The electronics, with an ATmega168, a temp/humidity sensor (SHT10?), a barometric pressure sensor, a combined USB interface / battery holder, and a pretty nice custom LCD:
Oh, and an 868 MHz OOK receiver module:
This unit includes some dataflash memory to store all received measurements and can be connected to a PC for reading everything out. I took it apart because the Windows-only software really isn’t my cup of tea (a not-so-exciting front end with Postgresql as database backend) and because the 3 AA batteries where running out a bit too quickly (why doesn’t it use USB power when available?). Besides, I really wanted to get a better 868 MHz radio. The module in here seems just right: it can receive all the KS300 and S300 data and it runs at 3V.
Maybe I’ll try my hand at de-soldering one day – the sensors might be worth salvaging as well.