A few thoughts, from this Canadian bus owner. Yes, there are many more options from the US with much better price tags. However we have recently been in the market for a new bus and were advised the process from the US to Canada is remarkably simple. We have NOT done this yet, but it was described as follows:
1. Go to the ICBC website and make sure it's a vehicle approved to come into Canada.
2. Submit the ownership to the border 3 days prior to arriving at the border, to have the paperwork ready when you arrive.
3. Go to Canadian Tire and have the paperwork verified (yes, somehow Canadian Tire is an option for this!)
4. Go and register at the ICBC, paying necessary taxes.
Also, this: https://www.riv.ca/ImportingAVehicle.aspx
However IF you are set on buying in Canada, Kijiji is our Craig's list, and there are opportunities through vehicle auctions.