Don't expect band directors to be able to read your mind about what is an "appropriate honorarium." For that matter, any payment should be pre-approved or it will go through additional scrutiny at the district level. To avoid this, present bill up front prior to clinicing a band and make sure you fill out your 1099 with the district so that you can get paid in a timely fashion.
ISD Business Offices
(Not saying you did this, Clinician, but this is frequently where the holdup occurs!)