Maybe look into mantis shrimp if you havent already. Octopus require a level of dedication few people can sustain. You'll read about some people here and there, but they're few and far between, and many are associated with the research community in some way.
This simply is not true.
You can go to TONMO.com for cephalopods specific advice if you don't find what you are looking for here. Cephalopods by Nancy King and Colin Dunlop is a great book as well. I haven't been active in the forum for a while, but several years ago there were quite a few people keeping them.
Depending on the species an Octopus is not much different then keeping a fish that requires specialized care. You can't just plop them in a reef tank, but they don't really need some kind of crazy level of dedication. Maybe if you got a GPO and needed a 1000 gallon tank and a chiller, but if you had that 1000 gallon tank and chiller they wouldn't be particularly more difficult then other animals from that environment.
I've kept 2 different Octopus Briareus. Both lived out their full lives without any major issues in my tank at separate times. They are a moderately sized octopus. I kept them in a 90 gallon tank. When small they hid a lot, but eventually warmed up. If you're feeding live food you just drop the fiddler crabs in and that's it. If you're feeding frozen food it may require some training, but once they are trained it's not any harder then feeding fish.
I also raised Sepia Bandensis (dwarf cuttlefish) from eggs, now they were more of a challenge because I had to have a constant supply of mysid shrimp shipped to me overnight internationally, as well as a constant supply of baby brine shrimp for the mysid shrimp to eat. Then later transitioned them to larger glass ship.
You need an appropriately sized tank that is built around the specific Octopus' needs. You also have to realize your Octopus will not be around long so after you will have to either look for a replacement or turn the tank into something new. After I was done keeping cephalopods I converted the tank to a garden eel tank.
