I personally don't believe that any difference between the Morel's and Aura's will be noticed. Therefore, I'd go with the cheaper ones

As long as you high pass the OEM rear speakers at ~100hz w/12 decibel slope I'd say stick with stock. That'll give you a bit more change for front components. There's tons of deals for front component sets if you know where to look. Give me a price range and I'll see what else I can find. But on the cheap, I'd stick with aura.

I have a set of a/d/s/ 320is I'd sell to a member for $120+shipping
a/d/s/ 320is - DIYMA.com - Scientific Car Audio - Truth in Sound Quality