[quote name='Javery']Effing sweet dude. Got a materials list by any chance? Once we redo the back yard I'd love to make room for one of these things.[/QUOTE]
Its really pretty simple.
2 bags of river pebbles or other smaller rocks. We bought 1 bag of large rocks(for $3ish)and an equal sized bag of smaller rocks for $2.00.
30 large/shaped bricks. I believe these were like $1.50 a piece but there were tons available from $1-$4 per brick based on how fancy you want to get
5 or 6 small bricks. You need these to serve as "wedge" pieces. Lining your bigger bricks up they will have gaps that need to be filled, unless your going to cement these you want to have a brick to fill that gap.
Thats really all there is to it. We bought a few extra of the large and small bricks that way 1. We would have enough to finish the project if we underestimated how many we would need and 2. To replace any if they got broke. They are cheap enough that I deemed it worth the $10 loss to not have to go back to the store

I imagine too that you could just as easily build a square shaped pit or rectangular or anything else. Really its just digging a hole and filling it with bricks and pebbles heh. O and in the middle you need a small hole that goes a few inches down, this is to give water a place to go when it rains!
Edit - Two optional things to buy.
1. Fire ring. For about $70 you can get a fire ring, the purpose of things is to have something to cover the fire up with and you could also use the big steel circle part it comes with as a huge wok hehe!
2. Cement glue. This thing stays firm without it, but we are still going to go back and spend the $7 to buy cement glue to ensure everything stays in place.