If you are taking on one student, that is a fair price. Personally, I wouldn't do a specialty for less than three people.
yes ,it would be nice if there were 3 or 4 students,and at times there may be, but more often than not for a speciality like this there is 1 student.With 3 or 4 students the costs to the instructor go up-more $ for pool-gear-etc..if course is scheduled and only 1 signs up,still should run it.Really should not disappoint the 1 that signed up.Their time is just as important as yours.