I always assumed Small tank prices were such to avoid making internal HTK too cheap, but that did leave the Standard fuel tanks feeling over priced. It's nice to see those costs revisited.
The new Tiny/Small/Standard costs look great, but I'm concerned that the bigger tanks now feel too cheap. It feels wrong that the material costs increase even slower than surface area.
So... I guess I'm suggesting the fuel tank costs be tweaked to scale directly with surface area, or size^(2/3).
Fuel Storage - Tiny: 5,000 litres, 0.5 BP
Fuel Storage - Small: 10,000 litres, 0.8 BP
Fuel Storage - Standard: 50,000 litres, 2 BP
Fuel Storage - Large: 250,000 litres, 6 BP
Fuel Storage - Very Large: 1,000,000 litres, 17 BP
Fuel Storage - Ultra Large: 5,000,000 litres, 50 BP
(costs derived at pegging 10,000L as .8, then rounding the other costs down)