The connection between OBD2 16pin port and a laptop can be gotten for $14:
Amazon.com: pc based obd2 scanner
The basic software can be free:
"OBD-2 Vehicle Explorer Scan Tool Browser Information Screen
Just remember there's generic code which all the scanners can read, and proprietary code for things such as convertible power top.
Some mfg (german) don't release the proprietary code easily.
A good logging software will allow multiple real-time graphs on the laptop screen showing what is happening concurrently and under what conditions(e.g. comparing load with ERG action with O2 response at WOT).