This site is very helpful. They give very accurate reviews for high end, overall, and budget equipment
Car Audio Reviews and Rankings - Bestcovery
My recommendation for your system on the amount you have to work with (if you are going for great sound over
what it looks like)
Head unit - the alpine cde-123 doesn't look the best or have the greatest features with it, but it
blows away anything near its price range in sound quality..
Sub - the sundown subs are some if the best out there for the price. But I would consider the JL Audio 3w2 I believe its called.
If you get a decent sub, having plenty of quality watts to push it makes all the difference. Getting a solid amp
to power the sub is going to be the hardest part on your budget. A new amp that will do the job good that is brand new
is going to take over 50% of your budget at least. Look around for used ones.
My advice? Join in on other threads and talk to other people, there are some cool people on here that will
help you out. Don't just post when you have a ? for yourself
Amp - just read about an amp that you can get for $180 that is really surprising for all it will do for the price.
The Boston acoustics 2200. It's 4 channels, don't remember all the specs, but I'm buying one. It can do 900 watts
when bridged and power a sub well, or push 4 or 2 high quality speakers
Speakers - Most important decision you will make in the system. You Must Get Component Speakers.
A lot of full range speakers are nice, but components are on a completely different level. For these I would
be patient because you will most likely have to buy used, but well worth it.
Apologies for the novel, but I hope some of this advice was helpful