If Ivy Terrace is appealing, some other options include:
1871house.com
http://www.bnbfinder.com/New-York/Ne...The_Gracie_Inn
innnewyorkcity.com
countryinnthecity.com
west-eleventh.com
http://www.innon23rd.com/

Have you contacted nyhabitat.com? We used them several years ago over Thanksgiving. I saw the website in a travel (may have been Fodor's I can't remember). I was very pleased. The apartment was as represented in the pictures and the people who I contacted when I called were very helpful. I checked and they still exist and there are apartments in your budget. You would probably have to get 2 but they would know of 2 in the same building. Also try VRBO.com.

Glad I could help. Have you decided on a property for your stay in NYC?

Hi, since I posted the question, our plans have changed a little. Due to one of the women's work commitments we have postponed to May 2011. Ivy Terrace is still top of the list though and we will follow up with them closer to the time. Thanks for everyone who helped. Cathie