Listen. If all you know about Barbie is the movie, you need to know this:
Old dolls really aren't worth that much.
Nope, not even the original dolls from the early 1960s, not unless they are in absolutely pristine condition.
And every second-hand seller is out there ready to take advantage of the idea, held by most people, that "old doll automatically means valuable doll"
"The price being asked on eBay" is NOT the same as "the price the doll is worth"
And, ultimately, dolls are cheerful pieces of plastic. They are not vital to life--if you don't know me, I'll tell you I'm saying this as someone who has had fashion dolls as one of my main hobbies for decades. If you think something seems a bit expensive, it's perfectly OK to pass it by. It's just plastic.
There has always been a problem, especially on eBay, of predatory pricing sought by people who can't even tell the difference between a doll made in the 1960s versus one made in the 1990s that uses a 1960s copyrighted body.
Don't fall for it.