Need a place for 2-3 weeks in June

Hey, I am heading to NY on June 1st and have a place to stay for the first week or 10 days. After that I need to find somewhere to share for about 2-3 weeks in Brooklyn. My budget is $100 per week for rent, is this too little. I don't mind living in a pretty cramped place andobviously don't expect anything fancy for this amount. Just need a place to stay until the end of June as I have a friend arriving over so we will be looking to share a place after that. Anyway would appreciate any advice or tips on neighbourhoods or places to look.
Thanks

Mark