G-Tech cost around $150, give or take. It gives you a fairly accurate indication of:
1/4 mile et and speed
instantanous G's and sustained G's
Do a web search on google or something to find the site, you can order from their web site which is what I did. I use it all the time.
I think I'm the only one that's actually trying to beat the 60-0 time, while every one else concentrates on the acceleration based numbers...