cost of addigng washer dryer

Unfortunately infinite if your building doesn't allow it (which many don't).

(and sorry I don't have an answer for you--everyone I know with a W/D bought with one already installed).

$15,000 for installing a washer dryer in the kitchen. From soup to nuts. When would you like have it installed?

Go ventless. Highly unlikely you can just vent out a window. If you do will likely not be legal.

I would make every reasonable effort to have a vented dryer. It will cost less to run and you won't be adding humidity to your kitchen -- sounds like a good thing in the winter, but highly undesirable in the summer.

All things being equal (and knowing that they seldom are), one of the first estimates to get is from your building's super. Is this possible?