Right now there's no longer a real 1m bounty active, and even the highest bounties are 250k~300k. For example, the 4 Toxic Horsemen are 1m combined, not individually.
Anyway, there's info in Hazard Pay, I haven't read enough of it to know if they pay for any blood mage, rather than just the ones on their bounty list. Also, given how you make it sound as if the Blood Mages are dead, I suspect that any blood mage NOT on a bounty list of DF/DIMR/APS as "dead" won't get them any cash.
As for the amount of the bounties, if we look at the Blood Mages in Hazard Pay we're talking 150k~300k for Magic 10~14 enemies, and some of those they want alive. Weaker ones may be only 10k dead, paid out by the cops or whatever. Capture is where the real money is for any weak mage on the bounty list, and weaker ones (such as the ones I suspect your players beat) may be 20k~50k each on capture. If you're at Magic 8+ and primary skills of 9+, then you're probably starting to enter the 100k+ alive territory.