Ricky Timms is famous quilter known for his designs and the On Line "Quilt Show" with Alex Anderson. Not sure if he even does individual guild presentations/seminars. If he does I am sure you would pay a premium for it. Here is a link to his website to learn more and see that he already does have a pretty full schedule with his own retreats and seminars at National shows
http://www.rickytims.com/
As Tartan mentioned, you should try to find out what the interest is. Many Nationally known teachers offer trunk shows which is a lecture and show and tell and they offer classes that in addition to a fee for coming the individuals attending will also have to pay a class fee. Some great quilters that come to mind are Sharon Schamber and Diane Gaudinski. Many guilds will do a combined thing with the lecture/trunk show for all guild members and fee paying guests to enjoy and then follow up with a one or two day class that members will have to sign up for and pay an additional fee.
Perhaps this link will help you in your search. It really boils down to what the general interest is for the event like Tartan stated.
http://www.karencombs.com/quilt_teachers.htm