I have a data logger of sorts from Innovate Motorsports. It hooks up to their gauges and controller and stores data on an SD card like those for cameras. The card plugs into any computer that will run Windows and uses free software to view your run.
With that, it's a bit tricky to use at the races. You have to start and stop it with a little button and if you shut the car off with it running it will mess up your data, Looking at the graph takes time to get used to because you have to learn to see where your burn out and stage stop and your pass starts. It would be better if it had an inertia switch to start it on launch and stop it on braking in the traps.
Gauge, controller and data logger go around $200 and that's cheap compared to RacePak stuff.
LINK:
http://www.innovatemotorsports.com/products.php