That's going to take some work. Air fare search engines are optimized for price between two airports (or proximate origin and proximate destination), not for segment count 'going anywhere'. Increasing origin/destination and/or date flexibility just makes the number of routings explode.

That said, I would look for O and D airports served by a number of low fare carriers (so FLL over MIA, BWI over IAD, etc.) and forcing DL segment counts with ITA Matrix advanced routing codes like this:



http://matrix.itasoftware.com/