Seeing prices of weapons and armor makes you think its gonna take forever, but wen actually earning gold is fast and easy, the obvious way is fighting, but another way to earn gold fast is selling items, preferably
Pet food- meat any meat- they sell for about 1,000 - 2,500
books- (make sure u dont need them) - 2,000 - 2,500
and five element cases - 5,000! (early in the game, if u fight alot, ull get about 5 or 6 of them, dont bother trying to open them, it cheats you by makin u pay 15,000 and it gives u 10,000, thts a rip off)
also makin your own store is good too, make them by the castle, put the prices high but reasonable (enough to rip off bigginer players

) hope this was helpful