Alright, first, on the local seafood restaurant, I would talk to them before starting anything and see what sort of products (fish/other aquatic animals and plant) they would like. If only wanting saltwater fish, it is possible to have a saltwater aquaponic system, you just raise saltwater plants or algae such as seaweed. You also might want to ask them things like how they would want their fish packaged. Sometimes, the way they want it packaged (or living) conflicts with local laws.
http://www.backyardaquaponics.com/forum/search.php is one of the more popular forums for help. But, I'd start out figuring out what kind of system you want to build (ie. simpler eb and flow, more commercial floating raft system, nutrient film, etc). Some systems will give you more plants than fish, and others will yield more fish than plants, so see what suits your needs best. Personally, I like good ol' flood and drain/eb and flow, and went with what looked simplest to me. This is a basic system:
That particular kind uses a bell valve. Some people swear by them, some people find they have too many issues with them. Mine just uses a pump and an overflow pipe. Since you don't want the roots constantly wet in this system, the pump is set on a timer (most use 15 minutes on and 45 minutes off), and you want the pump line connected to the bottom of the tank (instead of pumping water from above), so that the water can just drain back through the pump when it shuts off. Alternatively, you can put holes in your overflow pipe so it drains through there...but I just heard of too many people saying that gets clogged more easily.
Pipe diameter is huge. The bigger the diameter, the less your pump will have to work on overhead. A lot of people start with cheaper, smaller piping, and finds it gets clogged or puts too much pressure on their pump so that water barely trickles out.
Think about grow bed material. I decided to go with red lava rock (you don't want to use certain kinds that may leach heavy metals into your system...everything I read says the stuff from Lowe's is okay) for price and weight reasons. Hydroton is more popular for sure. So is pea gravel, but that weighs a ton. There are many other options, each having drawbacks and advantages. Most people keep red worms in their grow beds. The designs you see won't always mention them even if they are used. Generally, 12 inch depth is the desired grow bed media depth, with the water level only ever reaching 11 inches to keep the top inch dry and algae free.
You'll read a ton of conflicting information on grow bed to fish tank ratio and fish to gallon or fish to grow bed ratio. Well, more for the eb and flow systems. NFT and raft systems are more commercial, and have more numbers and grow charts for them. I am going for twice the grow bed gallons to fish tank gallons, and I'm shooting for 1 inch of fish per gallon (some push it much farther, others don't push it that far...my system is small, so I won't be trying for any more density than that).
Be aware that many commercial feeds can introduce heavy metals to your system, and can be apart of overfishing issues (for fish meal feeds). I don't see that discussed as much as it should be. I wanted to live feed using a mix of aquatic snails, red worms, self-cloning marbled crayfish, daphnia, minnows, and aquatic plants, but will have to wait til we move and I build a bigger system. For now, it will have to be commercial feed with sparse additional live feed for me.
Be aware too that there is some less than good and even dangerous advice on the web. One persona suggested using a diffuser hose instead of an air stone. Normal diffuser hoses will leach chemicals that are harmful to you and deadly to your fish. A food grade/aquarium safe diffuser hose is actually available online for cheap. You just have to be hyper aware of issues like that.
You won't have trouble in most states obtaining aquaponic friendly (ie. can be stocked in higher densities without stress) fish. Many won't cause you problems on freshwater crayfish either. Most will not require you to have any sort of permit if you are using a closed system. My state however, ended up being a huge pain in the rear for every step of the way. Apparently it is rather notorious for being super, nonsensically strict on such things.
Best of luck and have fun!