I was thinking about proxy as the development choice. Brandable as a proxy name. Reg fee imho. Could be more if the buyer is interested to make a proxy
If you could find an end user I personally think you could $xx,xxx for it. It would have to be someone looking to make some kind of spy software, for parents to track what their kids are doing online, or husbands and wives to keep tabs on each other. I would may contact some companies that currently have similar software and pitch your domain to them.