I'm sorry, but I defintely dissagree with some of the stuff jonc told you, obviously I doubt you are looking for a compeition system (judging by the amount of money you are looking to spend on an amp) so you don't need high high quality stuff like the stuff he has told you. You can get an alpine or pioneer deck from just about anywhere (try amazon or ebay for lowest prices) that will be absolutely fine for what your looking for. Look for a headunit that puts out 4 or 5v to the preouts on it so you can get a good strong signal to the amp. Also you don't need a crazy high powered amplifier for your speakers either, you can get a good infinity reference amp, or alpine pdx series(digital= low distortion amp) for a couple hundred bucks off again amazon, krutchfield, ebay, etc. Don't cut your doors apart and put 6x9s in there either. complete waste of time, money/ distroying your car, the 6.5s that are in there can provide you more than enough mids and bass, I gaurantee it! Also if you find a good 6x9 that's actually worth the money they probably won't even fit due to mounting depth, and you will probably have to custom make spacers, again waste of time and money.
Yes in a true very good system your tweeters should be mounted in your doors, and actually down almost below the dash next to your woofers in the door, but again you get more than good sound quality where they are, and you don't have to cut holes in your car and make it look like a 16's year old honda civic. Unless you are a professional fiberglass worker, or have had ample experience with it, this is not your gig, I can assure you that, it takes a GREAT deal of time and work to make it worth it (which still isn't worth it too me).
Keep your 6x9s in the rear if it was me, adds more of a surround sound, which I'm sure jonc will disagree, which this is preference, but again you have to make your rear panels look good (fiberglass etc) if you get rid of them.... again a waste. I'm not trying to say jonc doesn't know what he's talking about, he just recommends stuff for people looking for very high-end shit, and alot of custom work which most people will never attempt and honestly don't have the time, tools, garage, ability etc, to do it (not saying you don't). Right now I'm getting ready to install my speakers and amp I bought (check my sig) and it should rock harder than almost any car you've sat in I guarantee it! All are stock sizes and are replacing stock speakers and amp. In fact infinity makes some VERY good not over expensive speakers and amps, (I'd put mine up against just about anything). I am dynamatting my whole car too for sound of course, and again I do agree with jonc on this part, you'd be amazed how much sound actually escapes from a car.
Anyways not trying to bash jonc, just don't agree with a lot of his thinking, especially if your not looking to compete in sound competitions and buy stuff that you're going to need high powered alternators, extra batteries, way more than sufficient wiring etc.... obviously wiring is never going to hurt you if you go bigger than needed, but again 0 gauge wiring is also expensive to most. Just thought I'd post some insight too, I know jonc and I battle back and forth a lot lately with this, but it in the end is what YOU want. I do have experience with almost everything alpine, pioneer, sony, kenwood, jvc, jenson, dual (cough.... junk), pretty much everything that your local retailers sell, so I can give you all the info you want on any of these products and what I think about them.