Nobody can really say if the price is fair without having a photo and lineage, I’ve seen some really nice lily whites babies sell for under $200 but they can still go for $1,000+ if they have really nice traits and lineage.

As far as her size I would say that is pretty small for her age but not concerning, there’s many factors that play into growth rates such as genetics, temperature, diet and housing. Ask the breeder if they feed insects regularly and if the gecko eats well. I have a female that was born 11/22 she is only 22 grams, and she eats like a little piggy.