That's what it costs in Russia and North Korea. In the EU the costs are as I cited. And there are no production capacities at the volume required. China stopped exporting the specific type of cotton used for cordite production. Nitric acid is expensive and hard to get.
You can print billions of banknotes easily. You cant do that with millions of shells.
the difference is in different cost of workforce, different manufacturing standards, different materials, different fill, different fuze (easily 1/3 of cost),
GLSDB is cheaper than regular GMLRS rocket. ramjet 155mm is prototype. there's another obscure 155mm ammunition called vulcano that basically packs smaller HE sabot round in 155mm, trading off payload for range, ramjet takes it even further