I think a fine of $200 sounds good.
Star should also be able to do what she want with him (whether that be warn him or kick him out of the village).
Sound good?
I'd suggest talking to him first to make sure it's not a misunderstanding.
A warning is fine, and Star is certainly free to make her own decision about whether kick him from the village, warn him, or tie him up in the basement so that the fireworks' redstone current zaps him on every pass.
I think a fine is excessive in this case - he was/is a member of the village, and we don't yet know if it was malicious intent or not.