I have recently thought about burning some data to Blu-ray and therefore looked for some cheap blank discs. To my surprise, higher density Blu-rays seem to be much more expensive than lower density ones. In my country (Germany) for example, I could buy a 25 GB BD for 0,44€. A 100 GB BD would cost me 8,77€! At that price, it would be more efficient to store 100 GB on four 25 GB discs instead of one 100 GB disc (1,76€ vs. 8,77€). Sure, if it is one file I would have to split it first and combine it again when I want to access the data, but that effort seems to be worth it.
Why are high capacity Blu-rays so much more expensive, especially compared to HDDs or SSDs where the price per GB/TB usually drops with higher capacity?
Those are the exact ones. And I always paid between 7000 and 9000 ¥ (last order earlier this year was 8800¥) so this is the normal price. But your math is off, this is a 10-pack for 50€ (without delivery).