Hi Brian,
Lee Valley is pretty expensive, and there isn't a whole lot to choose from.
There are a few other places in Canada that sells pen parts. One is woodchuckers.com, which sell products from Craft Supplies UK. The website isn't great but they will send you a Craft Supplies UK catalog. The other is www.jacquescoulombe.com, which sells PSI products.
I've only bought a few things from woodchuckers, but I get most of my pen supplies from the states. There is just so much more selection, not only in terms of pen kits but also pen blanks.
In terms of customs, that's like a lottery. Recently, I received two packages. One I had to pay $40 in customs fees, the other I didn't have to pay anything.
Hope this helps.
Vincent