go with MB quartz or Infinity... specially if your not going to amp them, they will sound awesome with the stock headunit...but 10x better if they were to be amped
ps: and the dont cost n arm and n leg...
Most MB quartz are REALLY expensive, I don't know where you've seen cheap ones. The cheapest MB quartz i've seen are $999/pair for components. Amps=more power=more headroom=better sound. And they're louder!
(headbanging smilie here)
Expect to pay around $100 for a pair. More or less depending on the brand.