We have several servers and use software from multiple sources. Some of the servers are owned, others are on an annual lease to handle the various parts of the many perks we offer to iRV2 members such as our forums, chat rooms, photo albums, classified ads, campground reviews, etc. It costs us some serious money every month but through the generosity of our founder "Warpath" and our co-owner "rebelsbeach", selling a few banner ads, along with donations from some of our dedicated members, and coupled with a team of active volunteer moderators, we manage to keep the site up and running 365/24/7.
The only advice I can offer for your club would be to recruit a few of your members who are willing, able, and financially prepared to leave Yahoo and build a forum site on your own. Several of our Owners Forums have their roots elsewhere, a few from Yahoo.
'11 GMC Acadia SLT AWD
'11 GMC Sierra 1500 4x4 Extended Cab