Not low cost but I run Racepak with numerous sensors. It can be worth every penny for many different reasons. One I can think of one of my buddies cars had an issue where the car would slow down .3-.4 periodically. I noticed one time looking at his nitrous pressures it was always off with one particular bottle. Tagged the bottle and set it off to the side. The problem went away.
It's amazing how fast you can pick up on things, and improve your race program with a data logger. There is no guessing, did it do this, or that? It's proved it's worth for a clutch car.
