Miliaris morays of any kind are rare, especially the banana morphs. In the past 4 years I have only seen two bananas for sale. Just be patient and wait for the best specimen to pop up. A lot of the ones I see collected are what I call 'moldy bananas', a lot of brown and very small.
I found the perfect specimen about two years ago, I sold it for $750. I hope one day I can find another perfect one like that.