When I was a member of a guild, I was asked to teach a couple of different classes based on projects I showed during show and tell and I was not compensated, but the guild charged the members who attended. The guild did this with members for a number of years when money was tight. When they had the funds, they brought in nationally known teachers and paid part of the fee with guild money and members paid the rest, but they reserved 5 seats for folks who had taught classes for free -- I got to take some really good classes for free that way.