Sammael said:The math is right. I wouldn't allow it, though, because it's essentially the same as continuous mind blank, which would cost 8 x 15 x 2,000 gp / 2 (120,000 gp). The only difference is that it can be dispelled and then you have to wait a day to re-activate it, and that's not worth a 75,000 gp discount IMO.
All it does? It makes you immune to two entire schools of magic. That's not something I'd let a 12th level character be. Mind-blank is 8th level, and that means it's roughly appropriate for 15th-16th level characters. And even then it screwes up specialist enchanters and diviners way too much.AND all it does is stop mind-control and divination