I've taken several classes offered by my Guild and I think I would limit it to 15. If there is a great demand, then you could always have a second class. Check with your Guild to see if they have policies on payment for classes. Ours charges a fee of about $10. The fee helps keep members honest. If they pay $10, then they actually want to take the class and will show up for it. A free class gets alot of signers but they won't feel commited to showing up.