i have some good domains to make a forum
they have prices next to them but you can make offers....
the ones with traffic could drive traffic to your existing forum also


computingtalk.com - used to be a forum about computers and has links on other sites
price: $350

hostinggeeks.com + the logo on the site now
price: $110

website-talk.com gets hits and used to be a forum ( i think they changed domains)
price: $45

i can also sell you my owned vbulliten license with login to members area just bought it a few weeks ago of the site
price : $120


post / pm sold or make an offer
or will accept trades...