Sending sensor readings from Arduino to Raspberry Pi over 433 MHz
You could look into the RadioHead library - there might be a port for RPi, though I couldn't find one with a (very) quick google. This library works well, I use it actually with RFM69H 433 MHz radios (from Moteinos), a little more expensive than the simple 433 kits, but also supports encryption which might be important down the line. If you can't find a good library for RPi one solution could be to have a second Arduino acting as a receiver and sending data serially to RPi. This is what I use with a regular desktop PC which is my home server.

I also found a discussion about connecting a RFM69 to the RPi here which might give you more information about the process in general, even if you won't use the same radio.