This is a new one: an octopus farm. Kanaloa Octopus Farm is open for business -- for $200, you can get your very own pet octopus.
Unfortunately, they're caught in a chicken-and-egg problem. You should not encourage the capture of cephalopods in the wild, so it's a great idea to have a breeding program to provide animals for aquarists. But they're still in the process of building up their stocks, so they're selling their smaller wild-caught octopuses, which isn't so good.
Need I point out that you also should not buy an octopus unless you have the facilities and experience to care for them properly? I have a bit of experience with fresh-water aquarium management, which counts for diddly for raising marine species; keeping cephalopods happy also requires a lot of space and a large volume of clean salt water.
This is not like that time you won a goldfish at the arcade at the county fair when you were a kid, and you plunked it into a bowl of tap water and found it dead the next day. Well, actually, it's a lot like that last phrase.