Conestoga College is a great school and would be a good option. I don't know to much about the new milton Campus i imagine the school website will provide the best info.
I have a few different cost of living videos currently to check out. With regards to the different cities Hamilton, Brantford or St. Catharines are some of the more affordable areas on the West side of the GTA. I can't speak for many other parts of Ontario
