So, a room for the night was 4000 in game currency. I guess you could say it's around 4000 yen as well, since you can find some inns for around that price in Japan. If you convert that to USD, that'd be around 40 dollars. Just one potion is 120,000 of in game currency. That's something like 1200 USD if we're basing values off the room. Requiring 1.2 billion in game currency, it's no wonder nobody can afford it, I guess. That's enough to pay to stay at the inn with meals (7000 in game currency) for 470 years...