If you sell on
ebay or Delcampe or something worldwide, I would think, with proper naming and decription, a start of $2 would be OK, and probably more. Maybe $5.
I say this because of the nice blue colour and the pretty girl, a kind of 1890's postcard kind of look to her.
This would go well in someone's collection.
I myself do not, at this time, collect many ciderellas but when one sees some intriguing and well done stamp, I am always hoping mu wallet had grown since the last time I looked at it, poor thing that it is.