you shouldn't really be looking into oneof these, i hope you know that they are venemous and it can be fatal, they are for the advanced aquarist's definetly not for amateur's, if you still pursue one you should be careful, i definetly would not advise this species to anyone, not even those with many year's of experience handling ceph's, I personally i'm looking for one but that will be in the near future, not at the moment, if you really are interested have a look here:
http://www.dal.ca/~ceph/TCP/sources.html
also have a look here on info on the blue ringed octopus:
http://is.dal.ca/~ceph/TCP/bluering1.html
i really think you should aim for a ceph like a bimac (you do want it as a pet only right?), they are wonderful creatures, the Octopus bimaculoides make the best octopus pets for the aquarist. They are really cool to handle with, they are readily available everywhere, they are extremely tame, they are good eaters, they don't get very big but do get big , also they don't have a tendency to escape.
check it out:
http://www.cephbase.dal.ca/spdb/speciesc.cfm?CephID=508