It will be difficult to spend under $500 on shocks and springs both, so I can only recommend what I did.
I went with parts from Bavarian Autosport (
http://www.bavauto.com/) and I've been more than pleased with the products I got and performance of them.
Here is what I got:
---Front Shocks
$169.95 - Bilstein Front Shock - Left Sport - Monotube Construction
$169.95 - Bilstein Front Shock - Right Sport - Monotube Construction
---Rear Shocks
$87.95 - Bilstein Rear Shock - Sport
$87.95 - Bilstein Rear Shock - Sport
---Springs
$224.95 - Bavarian Autosport Performance Springs - Set of 4
This effectively replaced my worn shocks and loose springs with some sport shocks and springs that lowered my car ~1.5-2.0 inches. The ride is great now too!
That's $740.75 without taxes now. I think I paid something like $120 for both front, $80 for both back and $200 flat for the springs on one of their sales, so I got it for like $600 then, but you won't find many deals a whole lot cheaper than the $650-$700 price range.
They are actually offerring this whole setup now as a packaged deal for $652.27 (search for "Bavarian Autosport Suspension Kit"). Hope that helps!