I'd like to share a recent experience I had with Canadian Customs & Revenue Agency (formerly 2 separate entities "Canada Customs" & "Revenue Canada (IRS equivalent). If you drive over to bring stuff back in Canada, make sure you have your receipts. Online I had ordered $1200us worth of studio rackmount gear and had them shipped to a friend's place near Seattle. Of course the place mailed me the invoice to my home address in Canada. When I picked the items up, there was NO packing slip. We made an attempt to bring the goods back into Canada and because we had NO receipt, they detained us for over 2 hours while those lazy gov't workers went online to find an actual retail price of the item. Naturally, they chose the MSRP. Not only that they didn't take my word of how much I paid for the items, they also applied a 55% penalty on TOP of the value that they stated on the items. Add the 7% GST and 7.5% PST tax and you can see that I was burned pretty hard!
Mis-stating values on goods brought into Canada is NOT a criminal offense. Though they have the power to seize the goods and put a 100% tax penalty of the value if you want them back. Also your vehicle gets blacklisted for up to 6 years so each time you go across, a flag comes up on their computer saying that they are more likely to inspect your vehicle.
For goods that are over $2000usd in value brought into Canada, i'm afraid you will need a broker to clear the items (sometimes it slips through and you just pay the tax). Though looking at the other way, I find it funny how Canadian made goods enter into the US freely under the Free Trade Act - no tax.. no duties. For good reason, I don't blame the US for putting back duties on Cdn. made goods (ie. 28% duty on softwood lumber).
OK i'm trying not to go off-topic here. Just saying that in many ways, it's probably better to get the goods shipped to your doorstep and just pay the taxes than to bother with gas and time driving down.
For me, if only UPS and Fedex didn't charge so much for shipping from US/Can to New Zealand, then i'd have everything shipped there. (All goods under $300usd enter in free).
In BC, $20cdn is the threshold in value before GST+PST +$5 broker is applied (when shipped by USPS).
There are certain online companies like Digikey.com that are insanely great to Canadian customers. Somehow, you ONLY pay GST and for most orders, you only pay a flat rate $8 cdn and it's at your door step within 2 or 3 days (airmail). I have no idea how they get around the PST and broker handling fee. Other online places like Allied have a 3rd party company that sends you a surprise bill months later asking to pay for PST and broker fee.
Hope this info helps.
BQ