I have actually never done it but this is what I have heard the issues
a
1. Generally, you can't finance the purchase. US Banks wont lend money
on a Canadian registered plane and the seller won't get it imported
until you buy it.
2. It REALLY helps if the plane was built to US Ceritifcation
standards before being imported. That way you know it will meet US
regs.
3. You have to get what amounts to a mother of all annuals and a DER
has to sign off on it. The plane has to conform to US regs, which
means any modifications done to it under Canadian equivalent of US
STC, has to have a US STC too. If a change was made and its not a US
STC compliant change, then the change has to be undone.
4. I have been shopping for a Cessna 185 and it appears that they are
a little less expensive in Canada. The info I have is that if you take
the risk, and spend the money to import it, then you will save 10k, if
all goes well. If all doesn't go well, it could cost more.
5. I would call one of the Canadian brokers (Steve Assay or something
like that, they always advertise a lot), and ask him for a specialist
in the US that does these imports.
6. I met a guy who imported a Cessna 180 and he said it all went OK,
and was a good deal for him. His plane started out US certified.
7. You have to repaint the N numbers.