I think the bottom line at the moment is that anyone buying as far ahead as possible for the peak periods is very likely to have got a good deal. The tour operators are desperate to get people booking in advance rather than waiting to the last minute, hence they have genuinely offered some good pricing for early bookers. Also, and especially this summer, there is going to be VERY limited capacity for anyone not booked yet and those who booked last year will almost certainly be benefitting from the best prices. Conversely, the shoulder seasons (like September) are VERY slow at the moment, hence you may well get a good late deal if you can book for those off-peak periods.