If you have an android phone, you can get an app for it called torque pro, and a little obd2 to bluetooth adapter from ebay, and you will be ready to go for under $20. It supports realtime data, including O2 sensors, fuel trim, boost/vacuum, fuel pressure, intake temp., coolant temp., and it has a 1/4 mile and 1/8 mile timer that runs off your speedo. you can set it up with different layouts, different designs, and whatever info you need at the moment. You can clear codes while you drive, and it also has a website it will send you to if you click on the code to tell you what it means. For $20 I got the equivalent of a $400+ scan tool. I am in no way affiliated to the app, I just think it is awesome. It also has a hp estimater, and a 0-60 timer. Her is the adapter:
http://www.ebay.com/itm/V1-5-ELM327-...item3a8a613885
And here is the site for the app:
http://torque-bhp.com/