Everyone is going to tell you it's a waste, save up for [coilovers/air]. Different variations of this thread have been posted probably thousands of times on this forum - expect a few people to not-so-kindly suggesting that you try a search.
If you are keeping stock shocks, get VWR lowering springs (linear). They will only drop you about an inch, but the ride quality should be alright and the proper geometry of the suspension will be maintained.
If you don't care about accelerating the wear on you stock suspension, look at "Sport" lowering springs (progressive) - H&R and Neuspeed are very popular choices. This will get you a ~1.5" drop and is considered about as low as you can go on stock shocks. There is no good predictor of how long this configuration will last for you - there are many reports of people "getting away with it" for a very long time; other people swear you will be replacing shocks in 2-3 months.
The next category is "Race" (progressive) springs (again, H&R and Neuspeed are common), but ride quality will be pretty rough (this really, really sucks) and stock shocks are nearly certain to die quickly. This will get you a 2" drop, but you're really going to need performance shocks (Bilstein and Koni seem to be preferred).
Coilovers vary wildly in price. I would personally recommend that you steer clear of cheap coilovers. I went that route and now I'm in the process of undoing that mistake. Raceland and FK (and maybe ST?) are common "affordable" setups, but I personally wouldn't even consider this route unless you have ~$1,200 to spend on quality stuff (KW, Bilstein, et. al.).
Cup kits are another option; most will run the same price as cheap coilovers and most forum folks seem to recommend against them.
I don't know anything about air other than it seems to be expensive.
You can go as low as you want for ~$600, but unless your roads are smooth as a skating rink, your car will ride like garbage. If there is an ounce of shame in you, you will be embarrassed when you have passengers. Take the 1.5" sport drop if you don't have a lot of cash and want a decent setup. If you insist on going lower, you better be prepared to throw a lot of cash at it.
