According to Mark Twain, first-class lecturers on the lyceum circuit in the Reconstruction era (for example Henry Ward Beecher and Anna Dickinson) "knew their own value and extracted it. In towns their fee was $200 and $250; in cities $400." [Autobiography of Mark Twain, ed. Charles Neider]
$400 in 1870 is the equivalent of $7,473 today. Hillary Clinton must think she is about twenty times as good a speaker as schlubs like Anna Dickinson.