If you're going to be potentially purchasing the domain name, you don't yet own it ... and for this I'll need to move this to the "Domain Discussions" Forum. Please advise if I'm incorrect, and no worries at all.
Thanks and Welcome to Namepros.
I'd start low but not insultingly low, chances are they will counter offer anyways if they dont like your bid. I'd think they would want a fair amount for the name based on the success of CDGirls.com