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.

It is not possible to remove the fold from your eyelids to create the results you seek. There is no surgical procedure in the world that can make that happen.

There are operations to westernize Asian eyes but none to remove the fold. You have beautiful eyes and I know of no reputable surgeons who would touch them.