I think the problem is that for about the last 20 years, comparatively few bikes smaller than 600cc have been brought into the US/Canada. Remember that this is the land of "bigger is better", and even a 600cc is considered a "beginner's bike" by many.
The 400cc twins that used to be so common in the 80s have now changed owners multiple times and have been run into the ground. You just don't see that many in decent shape, certainly not for a measly $1000. Remember, too, that as gas prices have risen sharply in the US in the last couple of years, those few small bikes that get really good mileage are staying in the hands of owners who want a cheap commuter.
If you want a small cheap bike, think Ninja 250. These have been brought in continuously since the late 80s. You should be able to find one in decent condition for about $1500-2000. They are widely available and parts/service are easy to find. They're a pretty peppy bike for a 250, as well.
Bruce Clarke --- 2011 Kawasaki Ninja 250R (black)