Engine sensors and Arduino

Hey everyone - I'm looking to solve for something very simple. Get a HALL, oil pressure, and a temp sensor reading in to an Android tablet.

I'm aware of MegaSquirt, MicroSquirt, and speeduino but these are a bit overkill for my needs. They'll map cylinders, launch control, injection, etc. It's overkill. Not to mention the cheapest option is about $150 and everything else pushing $700+. I'll need two units for two engines. And I don't need any of that extra stuff. I just want a digital dashboard with 3 displays.

Any thoughts as to the easiest path? I'm expecting to need new sensors for compatibility and documentation.