Don't even think about buying shit off a hydro site. All you need are your buckets and an air pump for each one, or one that has enough lines for two. Simply buy the bucket from Home Depot with the top, this will be like 5 bucks for all of it, or 10 for 2. Get your air pump from a the aquarium or other store or best, online. If you want to make a top feed system, you'll need a water pump, I just got one from hydroponics.net for 10 dollars and it was originally $30. The top feed really isn't necessary, as someone pointed out, unless you have a reservoir that is recycling, otherwise your roots get plenty of contact with the water. I actually set it up in a 1 1/2 gallon bucket but didn't finish because you need to have it sealed off properly so you don't get excess flow, and it really wasn't necessary in such a small bucket. With a larger system to it would be more effective, such as Rough Tote, Just go on YouTube and look up homemade top feed system, nice tutorial on it. Okay now that I've said all that, you need your medium that you will grow with. Net baskets come in all different sizes, you want at least 3-4 inches for a good root foundation, You want to fill these baskets with your rock wool cubes and hydroton, buy the rockwool as close to the size of the net baskets and then cut them just accordingly. That's really it, all you need is to cut the holes in the top so the net baskets fit in.
net basket -
www.hydroponics.net/i/211101
rock wool -
www.hydroponics.net/i/111046
hydroton -
www.hydroponics.net/i/131574