I used to bring instructors from other dojos in the area into my dojo, and pay them to teach seminars. I did that a lot, wanted my students to see what else there was out there other than what we did. (please don't immediately dismiss that, it's actually really good)
I used to bring in EMTs, doctors, sports trainers, boxers, shooting instructors, cops (crime prevention) to teach seminars. I used to bring in Rickson Gracie, Bill Wallace and Joe Lewis. The best way to do that, if they're not already scheduled to be in your area, is to set up seminars in surrounding areas, say a hundred miles. It keeps the costs down, plus, if you do it right, you get to go to all of them for free, usually assisting them. (getting your butt kicked)