Yeah Atlas is very expensive. I'm pricing it the same as others at $40 but have room to move, in campaign its $25 extra. It has microcontroller, op-amp, ADM3260 isolator and a good 5v regulator, head to head with Atlas in 7.0 using same probe mine is more stable. :) I think it was because I had 5v regulator on mine and not on Atlas.
https://www.robo-tank.ca/Arduino-Devices/Robo-Tank-Isolated-pH-Circuit-Arduino-PI
I need to make a listing for the Reef-pi version but same thing without all the extras. Reef-pi version will also be shorter and no USB's.
One day I'm hoping to create a driver for EZO EC or convince one of you, I understand why you haven't. I already have an EC board in my box but still need to get equipment to compare against so on shelf for now, it will work like EZO but only $40 max instead of $100. I will give all files so you have, I know you like readily available. A lot of users I have won't convert to Reef-pi until it has salinity monitoring. :)