Cost of Surgery to Produce Monolids for the Eyes?

Unfortunately, I am not aware of any techniques that reverse the double eyelid and convert it to a single fold. That being said, you might wish to consider Dr. Stephen Park who has written some articles on Asian eyelid blepharoplasty. I am not sure of his location but you can probably google the information.

Unfortunately, there is no technique currently available that can create a monolid. There is only a way to create a double eyelid. 

You raise an interesting request. For the longest time, surgical techniques for doing the reverse have been taught. To the best of my knowledge, I am not aware of any surgical procedures. I could theoretically device one by detaching the fibers that create the upper eyelid crease but it remains theoretical and I would not advise it. I look forward to other surgeon's responses in this regard.