For a PS2-style humanoid/creature boss, including rigging and 5–6 animations, I usually work with a fixed price of $15 USD.
This includes the full character, textures, rig, and animations.
That said, I’m open to adjusting the price depending on your budget feel free to let me know how much you’d be comfortable paying, and we can see what works :)
If you have any references or examples, you can share them too!