You mentioned getting the Bones KS minis. I'd consider getting the blank monster cards (Enemy Threat Cards). These allow you to add monsters of your creation (or if you're able to see scans or copies of other's cards, you can make critters that are pretty similar to what's out there) to the game. For the $15 deck of cards, that's a pretty significant jump in new beasties to fight. This might help keep the game fresh.
This was going to be my suggestion.
For $50 you can get:
2x $15 blank monster cards
1x $10 blank gear/artifact cards
1x $10 encounter cards
This would allow you to make your own gear, and encounters.
Adding a lot of re playability in that regard.
And depending on what minis you used, the 2x packs of blank cards gives you 50 cards for each level. And you can use 1-3 cards per enemy depending on level.
So in theory those two packs could give you anywhere from 20-40+ additional monster / bosses to fight.
I plan on doing all this myself.
Using Bones minis you can create a nice variety to fight.
I am gathering a list of enemies using the bones I and II minis that can be added in based on otherworld and level. With how many cards I think I use of each. More cards makes them more often to come out.
And the different colors are different levels.