The pricing for national speakers/instructors is all over the map. We had Bonnie Hunter come to our guild. Trunk show and lecture one night, followed by an all day workshop the next day. She limited her workshop to a small number of students, and the tuition was reasonable. Ricky Tims, however, needed the guarantee of a whole lotta people, and the ticket price was high. Well, too high for me, but I hear he was amazing. It is lecture style vs. hands on class.
I agree with trying to get a feel for what the majority of members are looking for. Every state has nationally known teachers. If you start there, you may be spared the additional travel expenses.