Regent has a similar pricing/marketing strategy.
They start off with a very low price compared to brochure. At the end of every quarter, they raise prices. Not all cruise prices rise; just those that have sold to a sufficient level. If a cruise is not totally sold, they do not lower price again but may add other benefits (in most cases TA can add to existing bookings). I like the system as I know that by booking early, I am getting the lowest possible price.