Primarily for two reasons:
1) Membership in the FSW has value, as many people have volunteered their time and energy in creating an organization to showcase Wyoming and assist like-minded folks to relocate there. (If we're not worth the $25, then why even bother joining the FSW?) As libertarians, we believe in an exchange of values. (We also believe that the one-time $25 donation is a bargain!) And even though none of us is salaried, the FSW does have its basic expenses to cover, and the $25 helps to "keep the lights on."
2) Anybody can merely fill out a form and lick a stamp. The FSW, however, is seeking those who will do just a bit more than that. We want you to perceive value in us, and, conversely, we want to perceive value in you. $25 is not much money, but it is enough to weed out 95% of the tire-kickers and time-wasters out there. It's a "cover charge" to keep the quality of our membership high. FSW Members put their money where their mouth is!
Boston T. Party
_______________21 October 2007 UPDATE:
The $25 fee has been abolished.
Also, FSW membership is now done only online.
Please read the below for more details.
http://www.fundamentalsoffreedom.com/fswforum//index.php?topic=5283.msg38992#msg38992
Boston