Here's the system I currently have sitting in my room with the exception of the deck.
Head Unit: Panasonic color changing one. I forget the model number but it's a good deck, the sound is clean and it reads every cd-r I throw at it. The only downside is 2 weeks after I got it the LCD fvcked up and I had to RMA it. Damn RMA took 3 months to finish cus they were back ordered on the part. But all in all it's a good deck. (paid 200 something for it)
Mids: Stock. My stocks sound good.
Subs: 2 10" Polk Audio EX10's. I have yet to install em. I'm still trying to figure out when I have the time to build the box to put them in. (150.00)
Amp: Soon to be a Kenwood 300x2 amp. I know the RMS is only 150 watts. But that's good enough to put a lil low end into my system. Plus for under 200 bucks you can't really grumble. It's not the cleanest power source, but it's better than nothing.
(179.00)
I would go with a Clarion deck if you can find one you like. That's what I'm upgrading to. As for the subs and such, copy me and go Polk. They sound good. If you can afford the MOMO series of the subs then you're better off. But they're like 300 a sub or something like that. As for amps, anything that can cleanly power your subs, even the lowest amount of high quality power is better IMHO than something pushing 500 crappy watts.
-MzTyKaL