My first guess would be approx. $200 max -- maybe as high as $225 each (assuming they work, are in relatively good shape, and post-war). If pre-war, especially if pre-prohibition, maybe even more (but not for any "practical" reasons).
I'd only add that good head retention is closely related to the quality of the beer's "mouth feel" or body. A beer that has good head retention will likely show strong lacing (as long as the glass is clean of oils) and will provide a creamier sensation when consumed.
Congrats!
As far as the water dripping from the fan, you might want to try insulating the duct to reduce the amount of condensation prior to the air being vented outside.