You can search, it's been covered a lot al ready. But here is my quick notes with the suggested brands:

1. Springs - permanent drop (Ie: eichbach, Suspension technique)
2. Coilovers - Adjustable height (use springs and a base that you can turn to compress the springs to a lower drop - that's the simpliest explaination I can put it). There are sleeve coilover (AKA condom coilover) that to put over the shocks (struts) and bolt on (ie: Ground control). Full coilover system are struts with built in threaded body and base (ie: Tokico RAK501, Tein SS, OmniPower, A'pexi)
Shocks: Adjust the damping and bouncing of the ride. To use with springs or sleeve coilver only, and NOT NEEDED for full coilover (because they're built in) (ie: Koni yellows, Tokico Illuminas, KYB AGX)


Quality: Varies, you get what you pay for, so really, you can't tell. It's all based on the ratings of the springs' (coil) compression and the damping level of the shocks as well. My top 3 that fit the buget are: Tein SS, Tokiko RAK501, and OmniPower.