O.Mercatoris are warm water species so I don't know that you will find them in the Pacific. A recent post by a new member noted that danthemarineman (TONMO name) has some currently available on the East Coast (FL).
The Gulf Specimen Marine Lab is an interesting find. I could not find anywhere on the site that it requires official educational buyers (most labs have licenses that require sales to educational institutes only) but did note that there is a minium animal purchase $70. The joubini reference is suspect, in spite of the source, as the mercs are often referred to as joubini and the two are hard to tell apart (joubini is small egged and mercatoris is large egged). I suspect, but don't know for sure, that I may have had one for a short period (into the tank and never seen again). If so, they are identifiably different in that the joubini is smoother and larger with longer arms.
Be sure to start a journal when you start your octopus adventure.
i paid for mine the other day. he said it should mail monday or tuesday. he says he mails priority usps and not overnight. so if he mails it on monday ill receive it wednesday. im not really comfortable with that. but he says hes only had a few that were doa. is that safe to not mail overnight? that makes me really nervous. any sort of marine life ive always had shipped overnight. ive never heard of anyone shipping live stock anything but overnight. live rock two day, but an octo ?
Looks like you are ready. Nice to see a proportionatly appropriate piece of LR with lots of crevices. You might want to find a set of giant barnacles (the shells don't need to be very large) as mine liked them and were most visible when they would hang out there. Be sure you have some thumbnail sized shells for doorways available too.
Great to have a new merc journal (and hopefully two).