@xtheconman and
@firosahoge : this is mistranslated, the last comment should be "日本円で20万", 200,000 Yen not 20,000 Yen, so $2,000 not $200, this means that it is 2.5x as much as he personally earned from the sale of the animal materials in chapter 1 for those keeping track
@tonie 15 is the youngest age to register at the adventurer's guild (and the lowest age where you can go into dangerous monster controlled areas) but you can start training at the adventurer's school (which allows you to hunt [animals] (not [monsters])) at 12
For everyone complaining about the comparisons to Yen, Manga often bases this on the daily cost of living (price of an apple etc) and he is using his experiences over the 7 years (5-12) to make the comparison. For the sake of consistency the other worlds are intended to have the same scaled costs as ours (a house of similar size costs a similar number of apples in both worlds)