What franchise is the cheapest to buy?
Both franchisor and franchisee must due diligence. And because the franchisor is the more experienced of the two, the franchisor should insist that it be done. But once again, quantity not quality usually wins. (See ‘Buying a Franchise’.) Proper due diligence takes time, but that time is nothing compared to the results of a bad decision. Quality franchisor franchisee relationships are built on quality decision making.
It depends on the kind of franchise you're looking to get into, and what you consider to be "cheap". For example, the cold stone franchises are great (in my opinion) as they aren't as saturated as baskin robbins, and they have a way better product.
Others, though, I think have hit their limit...