Will you need pull up resistors to get the DS18B20 working reliably with the pi?
Also, why not do it wirelessly? You can get a decent WiFi Dev board for less than a fiver now days. I know that's another £50 down but surely worth it for no cables?
I always wire them like this and that works a treat. I believe you can power OneWire devices off of the data line, but I never really got it to work and it wasn't worth the hassle for me.
Will you need pull up resistors to get the DS18B20 working reliably with the pi?
Also, why not do it wirelessly? You can get a decent WiFi Dev board for less than a fiver now days. I know that's another £50 down but surely worth it for no cables?