I agree that looking at a generic cost/sf, especially for a rental is rather meaningless. You need to look at comparable units and even with that, there can be many other factors at play, particularly in a soft market like we have now and particularly in the Winter. Cost/sf does not take into account seasonal factors among others.
I personally think its always hard to clarify the sq/ft of a certain area because there is so many different aspects at play. Its tough to compare a newer 2bed condo, to a old vintage 3 bed rental. I think if you are looking for a good idea of rent per sq/ft you have to look at similar places in one area.
Americorp Real Estate
Brokers Associate, e-PRO