From The Heroes of Might and Magic III wiki
Fortress, Rampart and Necropolis
- First Aid Tent can be purchased for the cost of 750 .
- Oddly enough, Necropolis heroes cannot learn first aid, even though their blacksmith produces first aid tents.
Inferno, Stronghold and Tower
- Ammo Cart can be purchased for the cost of 1000 .
- Ballista can be purchased for the cost of 2500 .
- Cannon can be purchased for the cost of 4000 .