Hey Mate REXPECTED is clever in saying that the MB Quarts are the way to go
at this stage its probably better to leave the rears....unless your sitting in the back of the car you wont hear them. About $350 for a set of MB Quart Discuss and abour $140ish for the sub plus a box then a good 4 channel amp so that you can bridge the rear connections to use as a sub channel say about $400 + $150ish for fitting or if your technically minded DIY. My 2 Cents

If you want to you can have a listen to my system all mb quart and alpine.
pm me if you want a listen

Cheers Phil