I'll also tell you where I found the materials, since the wrong stuff can be super expensive at your local hardware store.
To give you an idea: John and I purchased all the pieces to make a single bracket from Lowe's, and the total was over $25. FOR A SINGLE BRACKET. And we needed five or six!
I was about to give up on my dream of pipe bracket shelving, but then I took to ebay, and after a lot of digging, I hit gold:
Yep, these pieces are called black malleable fittings and flanges, although you can rest assured they're not in the least bit "malleable." Some stores only carry galvanized iron pipe, which is a bright silver, and - get this - is more than double the price of black malleable.
So while it costs more than $10 for a single flange of galvanized iron, the same thing in black malleable is only about $4. Cha-CHING! (Not to mention I think the black version looks better!)
I couldn't find black malleable pipe at our local stores, but I did find an ebay seller who very nicely put together a custom listing of exactly what I needed for all five brackets, with free shipping, for fifty bucks. Ten bucks a bracket? Now THAT's more like it!
If you'd like to build the same brackets we did, then here's a handy cheat sheet.
For each shelf bracket, you will need:
(2) 3/4 inch flanges
(1) 3/4 inch elbow bracket
(1) 3/4 inch X 2 inch pipe nipple
(1) 3/4 inch X 5 inch pipe nipple
And this is the ebay seller I used, in case you'd like to buy from the same place. (Rest assured I don't get any kick backs or anything; just trying to save you some time, since it took me a while to find a seller who has all the parts I needed!)
Put them all together, and you get this:
Screw the flanges into a wall stud if possible, or use heavy-duty wall anchors. (We still have to paint over the screw heads, since you can see they're waaay too shiny.) Then use any old wood planking for the tops, or buy pre-cut shelves, and you're done!
Oh, and a quick safety tip: you'll probably need to clean your pipe pieces, since ours arrived with a fair amount of grease and a little rust on them, but be careful; the edges and seams are sharp. John sliced a finger while he was scrubbing, so he recommends wearing thick rubber gloves when you clean them.
I hope that was helpful, guys! And feel free to ask any questions in the comments, since I'm sure I may have missed something!