remove the word "perfect" with acceptable. your budget is too low for "perfect". that doesn't mean you cannot be happy for $300.
I put together a nice combination using Silver Flute 6.5" and Vifa ring radiator at a cost of $110 for raw drivers, plus 40 hours of effort on installation in the doors and spheres. Ran active they sounded good... acceptable.
Now I have Hertz Mille MLK-165's and they are as close to "perfect" as I have found. Love 'em. List is $850.
For really good speakers, your budget may afford you some nice sets used. I recently sold a set of German Maestro Status for $300. They had an $800 list.
Dynaudio, Morel, Hertz, HAT, Focal, etc. all make very nice high-end components. Their lower lines filter some of that technology down and some are decent. Listening to them is a good idea, just keep in mind the sound room and what is powering them.
but I will say this, despite all of the work I've done to my car to make the airspace as ideal as possible, and despite hundreds of hours of testing and trying different processors, amps, and speakers... all I needed all along were the Hertz Mille's.
I can't tell if you want two sets of components or one? $300 per set or total for both? You'll need all of that $300 for front components if you want your expectations to be met.
Also, recognize a great speaker installation is much, much more than deadening. The build logs linked in my sig give you an idea what I go through to get speakers to sound good.