You may want to consider a used pair of Tyler Linbrook Signatures... they are large stand monitors, but have bass down to -3db at 35hz. They should be around your price range.
The Merlins already mentioned are also superb speakers. They won't go as low as the Tylers, but have excellent resolution, IMO.
The Merlins already mentioned are also superb speakers. They won't go as low as the Tylers, but have excellent resolution, IMO.