not sur ehow many slots we are looking for, but found 

 http://clancomms.net/  (24 person for only 5.99/month.)


http://www.ventrilo.net/order.dml (50slot for $15/month)

http://www.nrgservers.net/vent/txvhigh.html (50 for $15/month prepay 3month 15% discount 6month 20% ...)