Is a seller allowed to charge extra for a bigger size without it being on the description page

[tracyakawren]

I want to buy 2 shirts, 1 med and 1 5XL. the seller tells me that it will be $5. extra for the 5xl. It does not say anything about the extra money anywhere on the description page. Is she allowed to do this?

[karl*katz]

Not Allowed