Kicker KX350.4 Just got one for $150 ish from locusaudio shipping included, Alpine has decent mid $200 range Amps. I really like the kicker, Bridge it up 2 channels and you should get enough power to run most things. Assuming you will only run 2 fronts. If not you can run it at 4 channels just as well.
For speakers $250 can get you quite a bit of choices. I like infinity Kappas. Many here would recommend ya rainbows etc...
Hit up a circuit city or bestbuy and test them all out see what you like.