I'd like to keep it free as long as we can. Once the membership numbers grow a bit, I will likely go to the fish stores and ask if they are interested in offering us a member discount, maybe 10%. I would also ask if they would donate either livestock or some sort of dry good (ie. salt, hydrometer, mag-float cleaner, calcium...).
If everyone is interested in putting in $3-5 for that type of thing, I certainly don't have a problem with it, I just don't want to scare anyone away, thinking that they have to pay.
Others feel free to chime in with your thoughts...