if you want to stay in Manhattan, you'll be hard pressed to find anything, but yeah if you take a look at any of the travel consolidators like kayak, orbitz, etc, they will give you some choices. But to be honest, i think $150/night is a bit optimistic. Unless you wanna stay in a dump, i think at least $200/night is more realistic. Plus remember that NYC has high hotel taxes tacked on.
the other alternative is to stay out near Laguardia airport in Flushing. There's a Sheraton, and I know a few other hotels. but if you were combining a trip to the US Open with some sight seeing in Manhattan, this might be a little inconvenient for you. But if you're coming just for the Open, this will be very convenient. It's just one subway stop from Flushing - Main Street to Willets Point/Shea Stadium (the stop for the US Open center).