If you are buying through Disney, I believe that Ontario is the only province they are registered to sell in. If you are outside ON, your options are to buy while you are at WDW (or DL) or to buy resale.
If you are interested in one of the older properties, you can still buy through Disney, but you may have to push the guides a little bit to let you do it. You can also buy resale, which may or may not be a better deal depending on closing costs, how many points are banked/borrowed, and price per point.
When we bought, we financed through Disney. A better option if you can afford it is to use a LOC against your house. The interest rate is usually at prime, which is considerably less than Disney. Disney financing though is very easy to set up, so you may consider going this route, at least at the beginning. There is no penalty for paying down or paying off early with Disney.
Be aware that unless you have a US bank account, you will need to pay your maintenance fees all in one shot in January each year. If you finance, you will pay that loan monthly. All payments can be made by credit card (including extra payments).
We are very happy with our stays at DVC. We love OKW and have never stayed anywhere else. I keep thinking about an add-on or resale, as we only have 150 points and sometimes it's not enough.