How Much Should My Premium Characters Cost?

Hi everyone! I'm the creator of the LOWPO asset packs on itch.io, including:

• Adventure Character Pack – 3 free characters + weapons
• Goblin Lowpoly Assets – free goblins + paid upgrade
• Other LOWPO-style character packs

I'm planning to release a small premium upgrade that includes:

• 4 premium characters
• Includes weapons
• Expands the existing free base pack

My question to the community:
What price feels fair for this kind of premium add-on?

• $2–$4
• $4–$6
• $6–$8

You can check out my other assets here:
https://standout7.itch.io

Thanks for any feedback!