Most jobs can be balanced with adjusted prices. I think the most balanced way for this job to be organized, would be good early prices and decent scaling. Something like: $5 per basic mob (creepers, skeletons, zombies, etc), increasing by 0.75 or 1 per level. To rival late-game jobs like woodcutter or miner, a "Hunter" would need to be around level 80 or 90.
Since only natural spawners would work with the job, I'd estimate it would be about just as easy and fast to kill mobs, as crafting axes or minecarts. The only difference being that the miner and woodcutter jobs require the player to craft things, sometimes throwing the huge amounts of minecarts or axes in lava, whereas the "Hunter" job would give the player more basic items, without the need to craft/destroy any.
