It's always a difficult thing when some organisation - often strapped for cash - asks a writer how much for a visit or a workshop or editing or somesuch task. Poets especially are too often taken for granted and asked to appear for very low fees or to publish a poem in an anthology or in a small circulation magazine for nothing or very little.
The Australian Society of Authors is a very professional organisation which helps published authors and those working to be published. They have posted their suggested list of chrages and fees for such functions at http://www.asauthors.org/scripts/cgiip.exe/WService=ASP0016/ccms.r?PageID=6054
Thank you, ASA.