The Sampo LME-17S3 handles Amiga 15khz as standart, but it does not come cheap!
Also does the Sony PVM-20M2MDU. As a rule of thumb, if a Sony PVM monitor has an analog RGB input, it will be a suitable monitor for old-school RGB gaming (ie. 15.75kHz).
Spanish industrial monitors suchs as Lazkun LZKPE19OF00.
Mitsubishi Diamond Scan 20M (model HC3925KTK), is a CRT max resolution 800x600
Sceptre C-NagaV 19" works in 15 khz
The one at this link http://www.converters.tv/products/vga_to_vga/474.html