DWDM Optics cheaper than CWDM Optics?

[Karl Gerhard <karl_gerh () gmx at>]

Hello,

fs.com offers DWDM optics that are cheaper than CWDM optics:
CWDM 80km 10G for 600$ http://www.fs.com/c/cisco-cwdm-sfp-plus-2425?70-80km
DWDM 80km 10G for 420$ http://www.fs.com/c/cisco-dwdm-sfp-plus-2485?70-80km

This is significant.
Is this for real? Has anybody bought their DWDM optics?

Going with DWDM and passive Mux/Demux seems to be cheaper nowadays than going with CWDM.

Regards
Karl