Well, I can't say that I've built anything or bought anything, but I can say that this system design phase is turning out to be harder than I thought! I finally received the Backyard Aquaponics book and DVD, and it was very informative and helpful. I recommend buying it, although it is $98. I guess some of that has to cover shipping from Australia. It's well done, and it definitely helps to solidify system designs and the things you need to think about in your mind.
I started off thinking that I wanted to design a small system and run it in a 5' X 5' corner of my shed. I live in North Carolina, so we have a winter. The idea of putting in the shed was attractive, in that I might be able to run the system year round. However, the shed was absolutely non-winterized, so I went out and bought some insulation and insulated it. It's much more comfortable in there now, and it's a bit cleaner and more organized. But, I don't think I can run an aquaponics system in there without having some sort of heating unit during the winter. That, combined with the fact that I would have to buy a grow light has turned me away from that idea.
Furthermore, when I started looking into the components I would need, i.e. a fish tank, grow bed, pump(s), and a light, I realized that building a "small" system costs about the same as building a larger system. In other words, no matter what size system you are thinking about, you're still going to need at least one pump, some sort of water tank, and at least one grow bed. In my crawling across the internet, I found that the fish/water tank was going to be the most expensive piece of equipment. Polypropylene tanks of food grade quality are quite expensive. I found some water troughs for livestock, but they had long, oval shapes and weird looking plastic. The sizes and shapes and cost were making the shed corner look less and less likely.
So, now we're thinking we'll set it up outside. As Mr. Malcolm realized, when you are setting up outside, the look of the components comes more into play. You don't want a bunch of plastic tanks sitting out in your yard, purely for aesthetic reasons! So, now we're leaning towards digging a 6' - 8' round hole, about 3' deep for the fish pond, and building a grow bed up against our existing garden fence. Also, we're leaning towards building a gazebo over the fish pond and trying to turn it into a nice space to sit and eat dinner. One thing that occurred to me that I didn't see mentioned is the notion of rainwater in the system. Like many places, we get some nasty thunderstorms here in the spring and summer that can drop a ton of rain in a very short time. That seems to me to be a potential problem with a closed, recirculating system like what I have in mind. That's one of the reasons for the gazebo over the fish pond (in addition to trying to keep down the amount of algae that will grow from sunlight).
The image at the top is a ridiculous rendition of what we have in mind (or at least the general idea!).