I mean, what the bounty would be was explicitly "Details To be Determined" If we wanted it to be about trying to entice Ranaldian grandmaster thiefs to infiltrate vampire hideouts for rewards to the tune of 1000s of crowns,... we could probably do that, it would just be a pretty inefficient use of our budget.
And since the thief will not be an expert on magical secrets you might end up stealing their cookbook anyway.