I cruise solo and I monitor certain cruises I would like to take. I start tracking after final payment date. As a result, I pay no single supplement. Currently monitoring a Canada New England cruise. Last week, it was 200%, now it is 150%. So, yeah, prices are sinking at least on this particular ship. As soon as it falls to 100%, I plan on booking.
Same happened on my Gem 10 day cruise a few months ago. I ended up booking 10 days out and paid no single supplement for a Sail Away balcony.