Hi Elena. I know you through Trulia's Questions section and you always have great responses to other people's questions. I won't reiterate some of the responses below but it does seem odd that a licensed real estate professional would ask such a question on an open forum like this. It may give sellers or buyers the wrong impression of your abilities.
Obviously there is a broad range of prices that would have to do not only with the apartment size but also building amenities, floor height, specific location, Condo or Coop. The list goes on but you already know this.
My question to you is do you think there would be a difference in price between a 2 Br Coop on the upper east side, walk up building and no Terrace on a 2nd floor and a similar sized Coop on Fifth Avenue with Central Park view on the 12th floor in a full service building and the apt has a Terrace?