You just need to agree to cancel the auction... no one get's charged anything except the listing fee, which for an auction is usually waved or less than a buck.
While I seriously doubt this is legit (buyer or seller shenanigins) there are cases where figures go for insane prices; I remember a custom Spenser did many years ago that ended over $1500... and he was charging like $200 for full figures. I couldn't sell a custom Jason figure when my asking price was $200, but then lowered it to $99 and the final price was $510; eBay is a strange place.