Depends on how much customization you want... If you just want new colors and a custom logo - a couple hundred bucks to have it outright. No subscription fees to bleed you dry over time. Couple requirements - you need to be running your domain on a host that supports PHP and MySQL. I'll even install it all for you and if you have a lot of domains and categories I can bulk load them for you to get you started... See what I did for Lance at:
http://tldnetworks.com/?page_id=184
If you don't have a host that supports that stuff, I can host it for you for a nominal monthly fee...