I think if i was to do a real native setup i would need at least a 75gal. Theres a species of crab in my area called a lady crab thats extremely aggressive so i cant put it in my 10gal.
The small size of the tank also keeps me from putting any native sculpins, flounders, searobins, or spider crabs in it.
I think one of the best things about a native tank is that everything's free and that theres no hassle when you need to get rid of something (such as a very aggressive crab thats killing everything in he tank), since you just have to bring them back to the beach!
Evemtually i wanna get a big tank and collect some Hippocampus erectus from the beach. I find them sometimes.