Well, any amp install is going to require a good deal of the car be "ripped out." A good shop, or even yourself, can put it back together just as well.
My usual reccomendation is Infinity components up front, coax in door, no rears, and sub/tube/basslink. Hard to get for 1k. Speakers will run you about 150-200 for the comps and 80 or so for the coax, 300 for a good HU and 300 for a good amp. You'll have great mids and highs, but you've ran out of money to build your bass. Sound is like a pyramid. It builds on the low end. Most people think subs are only for SPL, but they are equally needed in SQ apps. Anyway, add in a powered basslink for something around 250 and you're done. All of these are excluding installation, but if you can take about 30 minutes to learn how to take apart the interior (which is usualy very easy and only sounds complicated) then you will easily save yourself a good $3-400.
Of course, after saying this, you'll probably want to go HK. Thats not a bad price, but I haven't heard it, so I don't know if it is worth it. What I have told you is worth it and more.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>