So, I wanted to try the Fleet Corsair Flight Deck Cruiser. I could buy it outright, in which case it costs 20K fleet credits and 4 fleet ship modules. That's 2000 zen.
But, thanks to the ship sale, I could buy the original Corsair for 1200 zen then buy the Fleet version for only 1 module because fleet versions cost less when you own the ship it's an upgrade of. Right?
Only tier 5 Z-store ships count as a discount. Fleet corsair still costs 4 ship modules even if you own the original corsair. So I just wasted 1200 zen on a ship I'll never use plus 500 zen for a fleet ship module that I can't buy anything with.
It was all right there in the fine print. Stupid me for lazily assuming that fairness and intuitive logic applied to the situation. Please don't make the same mistake.