You can laugh if you wish. I have been involved in forums for many yrs. There are more people, like myself, that just wont waste their time. You see, what is there to motivate me to join? Many people "lurk" before joining a forum, they read, snoop around and if they enjoy it they may join.
Good luck with that.
If you cant afford to the cost of the bandwidth where you can allow guests to view the site, you are in for a short forum lifespan.
Ehfipimp #273 ( Eheim Classic: 2260, 2217, Eheim Ecco: 2236, 2232 ) Fluval FX5