You could have monthly membership fees and voluntary donations, but with bonuses for being a member bought with money from the association's bank account. Maybe the bonuses could be grouped and when the association is founded a choice is made that limits the direction and size those bonuses can go. Thus you'd chose to join an association that offered bonuses that suited your style of play. May be the diametrically opposite bonuses would be a minor penalty so there are pros and cons. These could be slots pay 10% more, or jobs pay 10% more or poker revenue is more etc. With the penalties being say 5% less of something else. Frequency of random events could be included as well.