I would start looking for second hand bikes on craigslist and kijiji. People are ending the tour you are planing and some will dump their gear. I have an urbanite for sale.

The most important thing to do is figure out your size. Go to online sizing programs, examine your current bike. Do some long rides. Get fitted at local stores. You can't buy a second hand bike, or other bike, without nowing your size, and you can't completely trust any one person in a bike store. They tend to sell to stock, and they know that a lot of people will need to compromise anyway. It is OK or necesarry to make small modifications, but you should only do it from a position of knowlege.

There are other brands up here than in hte US. Urbanite (http://ucycle.com/node/151), Rocky Mountain, and various Quebec and custom brands. There is a long tradition of domestic bikes in Canada, and anyway, most of the stuff on your touring bike is Aisan and the metal frame is a universaly well made item.

You are planing a tour that will take 3 months depending on what across Canada really means. So you need to work out a sensible timeline if you aren't to be completing it in the snow. Few people would really want to ride across Canada after first hitchhiking it. You will be returning by basically the same route, and all the camping can get to be a trial, unless you are born to it well experienced. Read some travel logs on crazyguyonabike.com to get some ideas. It is amazing the number of people who aren't up for a weekend of camping and cycling who will decide out of the blue to do a cross country, there is something motivating about the bigger trip.

The three most important pieces of cycling gear are a good seat, and that sorta means one you have proven you can ride day after day on, not just one you spent some money on. I have an 80 buck one that I don't find comfortable for all day. I ride a Brooks and do find it comfortable. I strongly recomend cycling shoes and some kind of binding. the improvement in comfort and efficiency is huge. I would get soemthing tour oriented or mountain bike oriented. I ride look touring sandles and find them very comfortable for walking also. I wouldn't choose hiking shoes since they are flexible exactly where bike shoes shouldn't be, but a cycling shoe can be designed for a minor in hiking. Finally, good, heavy, leather cycling gloves or something similar.