More recent books have included some "most wanted" individuals (including toxic mages) and none of the bounties approached 1 million, living or dead. And most infected bounties only go up to 15,000 so I'd be comfortable putting the generic bounties at 10,000 to 20,000 for blood mages / toxic mages.
As to a sinless claiming a bounty, given that the bounties in question are from the Draco foundation, I don't see it being a problem.