I haven't heard of any saltwater systems - finding salt tolerant plants would be the challenge.
Cost - people do it on the cheap with scrounged/salvaged components but others buy systems practically off the shelf and spend a lot more. There are many ways to build a system. I thought about it for a couple of years before constructing mine and my main expense was a tank - don't know exactly how much I have in my system but, excluding solar, about $2000.
Strawberries have started producing and my wife loves them = priceless.
Gregg, the thing about aquaponics is that it is completely customizable to your own tastes. You can have a system that is thousands of gallons or a desktop aquarium with a houseplant. Both are considered aquaponics. You can build an system for $15 or $1,500. If you like, take a look at the system on my page. I have some pic's posted. It ended up costing me around $1,500 total. Including fish, media, feed, grow lights, etc. A good first step would be to calculate how much space you want to devote to the idea. For your system, you want to use a 1:1 or 1:2 ratio of fish tank volume to grow bed volume. If you are thinking about doing a media based setup, your growbeds will be approx. 1 ft deep. And Ian is right...read, read, read. Pick up a book or two and try to get an overview of the whole concept.
Thanks Alex! I appreciate the information. I think I need to start at practically the desktop level to get me feet wet so to speak. I think I can work up to fish breeding and harvesting over time. I think at first I want to have ornamental fish that are cool to look at and grow just a few plants. Then I can work on something bigger as the weather improves. I have an enclosed porch that would be great 3 seasons out of the year, but right now I cannot heat it for the winter. I will check out you page and then I will likely have a few specific questions on how to set up a very small starter system. Can you think of a small plant or two that would be good to begin with? I am thinking some variety of goldfish or other tropical freshwater fish to get started with. Something I can buy at the local pet store.
If you want something that can be small and used often, consider an herb like rosemary or basil. Mint would be good. Stevia might be fun as a natural sweetener.
Thanks Alex for the ideas on everything. I like fresh basil, dill and oregano. But I think the smell of fresh mint would also be nice. I am going to do this indoors for now so it would be an added benefit.
I've been looking at material on tanks and systems. I think I like the idea of the system that uses a sump pump and tank to keep the water level constant for the fish tank. However, it is not clear to me how to use a standard tank for the fish tank, given that the flow of water depends the level of the water in the fish tank. How do I do this without cutting a hole in the glass near the top? See the diagram below for the type of system I would like to make.