Neither front door speaker in my newly-acquired Impala worked when I got it, so I went on the hunt for something inexpensive to replace them. There's no shortage or cheap speakers out there, but these really caught my eye:NVX NSP65
There aren't many reviews of these, however one thing that caught my eye was a reviewer noting that the speakers have crossovers for both the tweeter and woofer. This isn't something I saw in any other budget (or above) co-axial speakers. They also use a silk tweeter vs. plastic or paper, also common at the ~$35 price point.
I installed these puppies at work yesterday and WOW. Granted, I went from nothing to something but I have to say they really work well with the factory HU. I'm so impressed, I may buy a matching set of 6x9's for the rear.
So, just a heads up, if you've been looking for a new set of speakers you should definitely give these a shot.