Something else you can consider - stay in Jersey and ferry over. I stay in NY a lot for business so I'm not too concerned with the rates, but sometimes they've been so high that I've stayed in edgewater NJ and taken the ferry. Total cost was about half of staying in the city and in nice weather the ferry ride is nice.

Otherwise, prices are difficult. Just keep checking though as they change and you can sometimes cancel and re-book for less.