We have a Downtube Nova and are happy with it (within your price range).

Do you have special rider weight requirements Do you plan to ride on pavement only? Any plans to ride in very hilly areas or long rides (e.g. > 20-30miles)? If it's 'no' to all, you should not have a problem finding a bike that matches your requirements.

Origami's owner is a regular here so you may get a good deal.