I'm testing this one out now. Looking at a cruise (might be a back-to-back or piecing two together to make a round trip) with the first leg sailing in 3 days.

The cruise line's website has the best price for now over the above-mentioned sites. Might be something to do with local currency (historically, the line has offered a better conversion rate than actual market) and I haven't got VPN or using a proxy to see what pricing it is offering in USD.