Hi Greg,
You might have to deal directly with a collector to find O. rubescens. Here's a list of collectors that may or may not be up to date:
http://www.nhm.ac.uk/hosted_sites/tcp/sources.html
Since, as you surmised, this is a NE Pacific species, you will probably have the best luck by contacting the folks that are located in either Washington state or British Columbia.
There are a few caveats to consider before you commit to having one of these beasts though:
1. Since it's a NE Pacific dweller, it needs cold water. Figure on 55F or a bit lower. You'll absolutely need a chiller and that can be fairly pricey.
2. O. rubescens is an escape artist, even when compared to other octos. If you goof on your excape proofing it will find and exploit the gap.
3. As Feelers pointed out, rubescens is a biter and their bite can be quite nasty. They are also pretty smart about biting - there's at least one (confirmed) story about a guy handling a rubescens with one gloved hand being bitten on the other hand.
4. The few O. rubescens that I've been around have been VERY shy.
Qustion: Do you have O. rubescens on display?
Answer: Sure, he's in the beer bottle in that tank over there.....At least he was in there last week. We hardly ever see the little fella.
If you aren't otherwise interested in running a cold water tank or have some other need for this species, you'd probably be better off getting a bimac. They have a temperature range that's easier to maintain and they are a good deal less likely to either escape or bite the hand that feeds them.
Redily yours,
Alex
