blown speaker, worth replacing or upgrade? also want AUX-in
 

Right dash speaker is blown, so I'm considering upgrading all of them as the sound quality is pathetic and they're around 105k anyway. Also considering putting speakers in the rear. Can anyone with experience chime in, are they worth it?

Also wanting an aux in. I've heard the best way to get everything sounding better and to do aux is a new head unit, but I've never seen one that looks OEM enough for me. Suggestions are appreciated, the main goal is better sounds quality and aux.

Open to used as well, looking to stay under a few hundred for everything and would prefer plug and play rather than wiring up an amp. Tried to search but painful to do on mobile, if there are threads that cover my questions links are always appreciated.