How can I find franchisors that specifically do not use franchise brokers?
There are many franchise companies that do not work with brokers, in fact that's probably the majority of the franchise opportunities in the marketplace. It may be because they don't want to pay broker fees or it may be that their opportunity doesn't meet standards set for qualification or inclusion by the broker organization. I don't know of any clearing house that sorts franchise companies by how they spend money to attract new franchisee prospects, so you'll have to do a little extra detective work to determine whether a particular company is working with brokers.
In any case, there are a number of franchise internet advertising portals that have information on many different companies and opportunities. I'd also suggest a good general print publication listing of franchise opportunities. The best and most inclusive in my experience is the January issue of Entrepreneur magazine (the Franchise 500 issue). This lists important information from over 1000 different franchise companies you can review at your convenience.