[jmz5]

Right now about the only viable option is from Tooltech.

3-Dot price for the FN57 is $287.00 for parts, labor, and installation Plus $17.50 for shipping, handling, and insurance. The front sight as well as the rear sight blade will be replaced with a custom three dot adjustable night sight set.

http://tooltechgunsight.com/index.php?option=com_content&task=view&id=24&Itemid=52