The generic picture shown has an extra part in it that is not on the list and looks like a Panhard bar that is not applicable to our vehicles. What are "nitro slammer" shocks? Beware.
At the shop, we like the OPG stock style sway bar kits. They are a good value when they are "on special". For stock height springs, try a retail parts store with a brand like Moog, Dana or McQuay. If you really want lowering springs, OPG and Summit offer them. KYB shocks are a good performing shock for the money. If you go 3" lower than stock on the rear, you will need shorter rear shocks. The stock length front shocks will work at most any spring height.
My advice, put your own "kit" together. Sway bars and shocks are more important than springs if you have to keep your spending down to $500 or so. Then get the best tires you can afford.
The next big step for improvement in cornering ability is to change the "camber curve". There are a few different ways this can be accomplished.
Thanks for the responses guys, I'm not afraid of spending more money, I don't want cheap parts but I don't want overpriced parts either. I'm new to this performance thing so just trying to figure out what the best value is.