The Atlas Scientific PH kit is quite pricy, I mean I can get 5 stand alone Ph-meters cheaper than the Atlas Scientific PH kit + probe.
Ph circuit @ $28
Ph-probe/sensor @ $10-60 (Depending on quality)
Arduino @ $15
Building it this way will set you back atleast $60 + the work you put in to it.
Do you think it would be possible to use an external PH-meter and “hook in to it”? Perhaps hack in to the LCD of the PH-meter or hook up to an IC and steel the values in to the Arduino?
I read an instructable about hacking in to the “Kill-A-Watt” meter, a Ph-meter should be possible to hack also?