the price of roasted coffee is natural?

that price difference reflects many things: green bean (commodity vs specialty), cost production and overhead, brand positive, and channel sales. That Rp 30 grand is probably non-specific commercial coffee, which is 300,000 maybe micro- lot geisha or rare original specialty.

how to calculate simple prices: HPP = cost green bean + overhead + labor + packaging, then add the margin you want. For specialty, gross margins on the roastry level are usually 50-60% of the selling price.

the price of "fair" is contextual. for direct-to-consumer online, specialized roasted Indonesia original standard Rp 70-150 thousand per 100g that's a common range. But this could be very different depending on quality, brand, and channel.

one thing to note: if selling is too cheap early to attract buyers, it can be hard to raise prices later. that pricing is also brand statement.