BimbaMore on train ticket prices.
From Berlin to Bern, which is about 1,000km, one can go for 40€. But to get from Poznań to Berlin, which is about 300km, one has to pay at least 108zł (about 25€ today).
Tangently, it's possible to go from London to Oxford, which is about 100km, for 7£ (about 8€ today).
All prices way in advance (pun unexpected)