I have a pair of Dali Helicon's. They sound great even at very low listening levels. You should be able to find them used or new in your price range. I have the 800's but depending on how big your room is even the 400's could do. I've listened to some Dynaudio S5.4 lately. Very good sounding speaker too. There you could also go with the S3.4 depending on the room. I would audition all of them if you like a neutral sounding speaker. The Dyn's need more power though to bloom.
Mike
Mike