Better bring a big sack of $$$. If you plan on motels every night, its going to cost you big $$ in the US/Canada. I'd think it would be impossible to do the trip on a budget of less than $100/day if you're staying in motels a lot. And that $100/day figure is probably low.
IMHO, this is the best time of the year for tent camping, and you'll have much more contact with people. Generally speaking, one can stay at a commercial campground for $10 - $20 US per night. Motel rooms are rarely under $50/night. In touristy areas and big cities, expect to pay $100 and up for a room. On weekends, especially in tourist areas, motels are booked well in advance. Special events can eliminate all available motel rooms in a 40 mile radius. These special events nearly always take place on weekends.
If you stay "off the beaten path" in your tent, its free. This option is only available in rural areas.
In the Yellowstone area, the town of West Yellowstone is where the least expensive motels may be found. $50 range & up. The motel within Yellowstone Park, the Old Faithful Inn, I believe, charges around $150/night.
You'll be eating most of your meals in restaurants. Breakfast will run $5 - $10 after tax & tip. Lunch will be about the same. Dinner will generally run $10 & up.
Gasoline will likely cost around $3/gallon. Of course, gasoline prices are volatile. Political turmoil in any oil producing country generally sends gasoline prices higher overnight.
I can't fully promise it yet, but if I get my guest room over my garage completed in time, you're welcome to do an over night stay. I'd even furnish you with a home cooked meal, and high speed internet access. I'm located about 30 miles south of US Highway 2 in Wisconsin in a rural country setting.
I'm also convinced the US has very inexpensive prices on used motorcycles and that from an economic standpoint, it is far cheaper to purchase a bike in the US, register it, insure it, and then sell it before you depart. I suspect shipping a bike to the US isn't cheap. Neither is its return trip.
Granted, there is nothing like being on ones own bike, but one should examine the big picture.