It is cheaper to build the Digital Carb Sync kit yourself. If you want to pay and go faster, this is your option.
This build includes a complete assembled board ready-to-use with 4 sensors mounted, a compatible Arduino Uno R3 pre-loaded with the standard software, and a red 3-D printed case.
All the instructions for use are on the website. Order the download package if you want to get all the files.
Open source license terms apply.