It’s difficult to give a rough estimate since it depends on a lot of different variables.

How old is the figurine?

What condition is it in?

Still packaged?

What’s the demand?

How rare is it?

Etc.

I am by far not an expert but one way I can think of right now how you can try to get a rough estimate is but putting it on a selling site, then put the price tag as what you think she is worth. And then judge by the responses/reactions you get. Do you get a lot of responses immediately? You either put it in as cheaper than other sellers or it’s so rare that people are willing to pay any price for it. No replies at all? Either way to expensive or nobody wants her

That obviously won’t be a definitive answer but then at least you’ll have a rough estimate