The border works just fine for both exporting and importing if you are patient and do not play any stupid games. We want to pay any GST that is owed (there is no DUTY on items of numismatic interest)when we come back from a US or European coin show. Also declaring large amounts of currency in and out is a must. The limits are 10 K Canadian out of the country, 10K US into the States and 10 K Euros into the EU including Great Britain. Needless to say when you come back to Canada it is 10K Canadian. The forms that you fill out vary. The only way around the currency declarations is to have a legitimate declared foreign bank account that both the IRS and CRA are aware of.
Another problem a lot of people on the forum do not understand (related to border issues) is taxation issues related to coin buying and especially selling , is the threshold levels, that might get into issues with the CRA (both income and GST/HST) and provincial authorities. Take for example BC. If you are doing MORE than ten thousand dollars a year in sales you MUST have a BC retail sales tax number, if the threshold reaches 30 K then you are required to be GST/HST registered Federally and procure a BN or business number. There are more than a few Canadian sellers on
ebay and coin show and flea market operators, that probably have no idea about this. Hope it helps ! Have a good one everybody !