Hi Nate,
If you have access to electricity and invest in a chiller there is no reason you can't have a locally stocked cold water tank.
There are fewer corals in CW but there are many colorful anemones, macroalgaes, starfish, sponges etc...
I haven't had much in the way of problems in regards to collecting. It's really just common sense. I've talked to our DFO (department of fisheries and oceans) and have even met officers on the beach. They weren't really interested in someone occasionally collecting individual specimens and I imagine it is pretty well the same up there as long as...
You are not over harvesting
You are not collecting for commercial purposes
You are not collecting endangered or threatened species
You do not reintroduce collected specimens back into the ocean
I have a different approach than some (I suppose). Instead of rushing out and filling my tank to make a pretty picture I have added some species and just watched how they do over the long run. My tank is like one long experiment. My goal is to run a 60* F max. tank rather than a 50 - 55*. Doing so does a couple of things like reducing the amount of condensation on the glass and working the chiller too hard in the summer.
I've had Ochre and sun stars thriving for a year as well as surf anemones, tide pools sculpins, sticklebacks, pricklebacks, hermits, limpets and various shrimps. I initially collected specimens from the inter tidal zone by beach combing and now dive to collect as well (nothing like two expensive hobbies).
There was a big thread on coldwater systems somewhere here. I'll try to edit in a link if I can find it.
Here it is:
http://reefcentral.com/forums/showthread.php?threadid=890751