Fair point, what I am saying, Yes, I agree OEM part has probably the best quality (and warranty), customer should be informed of an option of using cheaper 3rd party part. The warranty expectations of the aftermarket part should be discussed with the customer and limited to say 1 month or so?
In my very limited experience, every single aftermarket part I've ever bought (about 4-5 over the years - bulbs, gaskets, wipers, Oxygen sensor, light housing, and a few more) worked and fit perfectly well. Back when I owned only a cheap '99 Toyota car, It came to the point that I'd pay for diagnostics, buy parts myself, and pay for install time. Still saving money.
Not every single car mechanic overcharges on parts, but from my experience many do.
Another point is some cars, let's say complex euro models like BMW or Audi for example - you'd want to use OEM parts, if not new at least refub/used part, but something tells me that using 3rd party parts on 17 years old KIA isn't big deal at all.
In my option this reminds me of using aftermarket laser toners - I've had my share of bad ones, but 95% of the time they work just as well and cost MUCH cheaper.
