Since dry dark field condensers are limited in their NA they can not be used with high NA objectives. This means that dry dark field is a commercial non-entity. It just doesn't sell, however all good manufacturers make it so if you need it you can get it. Oil dark field is the tool of choice is you have to do dark field. The only draw back with oil dark field besides the general problems with dark field is that oil dark field condensers will not work very well with low power objectives.
Most manufacturers make a universal condenser.
These condensers are usually pancake types that contain phase, Nomarski and simple dark field. This may be the only Nomarski condenser the manufacturer has. The phase and Nomarski will work quite well, the dark field won't. You can't put a modern dark field condenser in a pancake type condenser. If you need real dark field and bright field you will need two condensers.