Hiya Trixie
I'm not sure about taking an appraised domain you already own to a bank and borrowing against it. What I've heard is that their appraisals are being used by companies that offer financing to purchase more domain names. For most people it probably would be harder to find a banker who understands the adult business well-enough to realize why some domains/websites are worth so much more than others.
You might check with
www.domaincapital.com (a Moniker partner) which does mention on their website that they offer funding services to existing domain owners too.
HTH