So if I understand this correct. Royal Space Force blu will still be $13.99 when wave 3 is announced? (Depending on stock of course)
That is exactly right, with the added exception as well for certain titles if they go out of stock, and come back in stock, it may be a different price, but this typically happens more often with ViZ and NISA titles.
The waves of Rightstuf sales prior to the past few years did not coincide with the 12+ sales, but in the past few years they have started to extend all of the Wave 1-3 items into the 12+ sale as well, so that will be something else to keep an eye on.