Yep, I think prices here are a little higher than what you'd pay in the States. This is my thought after seeing all the listings States side. Yet, the market here seems to shy away at times (not always) at a US car with "Miles" instead of "Kilometers". This appealed to me when I bought mine. My thinking is that it is local and carries it's history, whereas you may not really know the history of an import. Again, that was just my thinking at the time I bought. The car and owner was known to the local Porsche dealership in Calgary which did the PPI. The other more important conditions I wanted were G50 coupe with LOW miles: I got 1987 coupe with 51,800Km. I paid close to asking price; I didn't get a steal but I didn't lose my shirt. In the end I'm happy!
I'm not familiar with the work involved in importing, but I know there's more than just exchange rate; there's taxes (both in BC) and duty, and I think something else, not sure. So it adds up quite a bit in the end.
Now that I've owned a P-car for over a year and have gotten to know them somewhat, I would not be afraid to at least look State side and see what's involved. Who knows, maybe my next one will come from there. The machine is still the same regarless of odo/speedo. You just need to know what to look for.
As for your 89-930 cab mic, they typically fetch $15k over a non-turbo of same vintage/mileage/condition. I agree with gorfllub, you'd probably get well into the $50K range depending on condition.
Vancouver has a decent "population" of Porsches. Check out the local shops and see what they list at. Try these links:
http://www.weissach.com/
http://www.urbangarage.com/
and autotrader.ca of course, which is where I found mine incidentally.
Hey! Have fun and enjoy these cars!