{Autozone and most other Parts stores will do it for free.}
Parts houses have neither the equipment or skilled technicians to do real time data logging, which is how difficult diagnostics is done. While true parts houses can read basic OBDII codes, proper diagnostics is far more complex requiring multi thousand dollar scanners, technicians trained to evaluate the results, and software subscriptions in the $10,000 per year range.
The benefit of a couple hundred dollar diagnostic fee can be offset by not shotgunning $500.00 ECMs at a vehicle or using used parts that may further exacerbate undiagnosed issues. But you are welcome to roll the dice with the kid behind the parts counter and his $200.00 code reader.
I was not referring to RT Data collection. Been there done that.
I did 18 years selling parts and 12 turning wrenches for a living, mostly on high end stuff. Jag/Rolls/MB/Porsche/Ferrari/Lambo’s as well as Domestic.
They ALL breakdown it's just a matter of what and when. It could sell for $500,000 or $ 50.00. It's still mechanical/fuel and electrical.