Hey I saw this I am just getting started in hydro and used dwc but if you get enough extra nozels for clogging this will work : http://www.hydroponicsearch.com/Explore_the_Science_of_Hydroponics/Homemade_hydroponics_%26_aeroponics_system/Homemade_aeroponics_system/

For a medium that is cheap, bark chips. You can use the black 5 gallon plastic bags for holding the chips. Then setup a drip system. How many plant sites are you looking to do? With the chips, the roots should get a lot of oxygen to the root structure. It's a real simple setup and pretty rewarding. I seen a greenhouse in Mississippi(Mississippi State University) that had tomatoe plants growing in the bags and they were huge plants.

I'm looking to do four, one with grow rocks, rockwool, vermiculite and perlite.

I was thinking about buying one like this,
http://cgi.ebay.com/Hydro-Tech-Hydroponics-system_W0QQitemZ120168506562QQihZ002QQcategoryZ43555QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

eh?

I HATE spending money on things that I can build I would do a pupm with a timer so it pumps into a large barrel that is on a table thats has 1/2 inch micro irragation pipe with 1/4 inch noodle line that has drippers on the end. It would be easy for the holes,buy a $2 hole punch for the 1/2 inch black tubing from home depot. For the buckets go to a food place and ask for food buckets.

Try this web site.

Here is a link that might be useful: Hydro Ideas

I did an experiment with different growing media. I made a wood trough lined with plastic for each media though you could probably use a single trough and put the media in something like a paint strainer bag to keep them separate. As for cheap and commonly used media, I like wood chips. You can buy cypress chips cheap but I'm also using free wood chips that the tree service will dump at my house whenever they are in the area. I've also used spanish moss as media but it can get kinda nasty so is better for a very fast crop like lettuce or radish.
Anyway, my system with media consists of;
1-A trough. (three of those $1.59 fence pickets and a couple scraps of wood to hold it together.)
2-lined with plastic and a bit of fiberglass window screen at the bottom to keep media from falling into the resivuar. (if you used paint strainers for the media you probably wouldn't need the screen.)
3-a bin for the nutrient.
4-This is the $$ bit, a pump. (it runs 24/7 so no timer needed)
5-Some 1/2" irrigation tubing and fittings to connect to
pump.
6-shade cover of some sort for the resivuar (just keep light out of the nutrient.)
7-paint strainer around the pump.
8-some way to prop the trough up so nutrient can flow in at the top of the trough and flow out of the trough directly into the resivuar at the bottom.

This sort of system is pretty cheap other than the pump. There are many things that can be added or expanded but the basic idea is really simple. It is also easier to keep roots from clogging the drain pipes as there are no drains to worry about in such a basic system. It is modified NFT or a trough with media.

Good luck with your project whatever you do.

I only use river gravel. it doesn't impact the ph of your nutrient. its relatively heavy so a good base for roots and it easy to sterilize for repeated usage. oh! and its cheap on small scale projects. i grow tomatoes, parsley, basil, and (currently) green peppers in netpot filled with river gravel.
my tomatoes were grown with a deep water culture system. my peppers are being grown using an ebb n flow system. pumps shouldn't be too expensive. around $20 to get them shipped to your house. to avoid having to buy a decent timer (intermatic 14 setting is about $26), use a modified ebb n flow system as mentioned in the post above and just set the netpots with rivergravel in it.
good luck, let us know how it goes

Here is a link that might be useful: