ya....sounds like a plan...the front ones are trash
so new speakers for front doors
and an amp to power them.
and a new head unit.
i dont understand how to upgrade the wiring, since everyone says what i have now is crap. whats some good wiring to get?
Hmm....that is pushing it in terms of getting good stuff and staying within your price range; I had forgotten that you really want to ditch the HU. A friend of mine was in this exact same situation and we decided to just go with a nice Kenwood Excelon head unit and save the rest of the cash until he had more available. Honestly, seeing you have a better system than stock as it is, I would definitely suggest the same thing (and moving the alpine speakers up front). Look at all the Kenwood Excelons except for the KDC-X991 (its their nicest one and its what I have, but its expensive and not worth the extra features for what you are doing).
I would do the amp's the other way around. If you have to choose between a nice amp for the components or subs, always put it with the component speakers. I spent 3x as much on my components and amp for them than I did on the sub and its amp. Here is a complete run through of what I would do for the time being:
1) Find a good head unit; it will probly be in the $180-250 range. Look for the features you want, but
make sure it has either 4v or 5v RCA outputs. Im pretty sure all HU's have seperate front, rear, and sub rca's now, but just make sure.... Also, all of the kenwood excelons (I think) can read files from a flash drive; so unless you really want the ipod itself to use other places, just spend $20-40 on a big flash drive.
2) Move the shitty speakers to the back and use the head unit's built in amp to power them.
3) Move the alpines up front. I would suggest testing them on the head unit's amp as well (It will have 4 low powered channels, probly 20-30watts rms each and 50w peak each or so). They wont sound perfect, but if they sound decent I would just leave it and save the money you would have spent on a half- ass amp for the half assed speakers. IMO, it would be dumb to spend money/plan any part of your build around speakers you dont want to keep in the long run if you can help it.
If all of the above works out well, you shouldn't have spent more than $250. Then, I would save up until you have the cash to purchase some nice component speakers (for the front doors) and an amp for them at the same time. Just some brands to take a look at when you get to this point: Rainbow, Focal (polyglass line), MB Quart (not sure how much the q-line is). Obviously go with 6.5's if you can fit them. As for an amp for them, JL amps are pretty good. the 300/2 is a quality proven amp, and represents a pretty good value, but would probably be a little overkill for any speakers you are looking at. See what they have that is a little less powerful.