It can be rather irritating at first, but at lvl 15 you unlock scythe which allows a lvl 15 to grind mobs far higher level than them. In my instance it was giant fire ants. Each feeler dropped was 2ryo and after grinding from 15 -> 20 in about an hour or two I had a ton of ryo to spare. I only really use wind-shuri for pvp anyway so it's not too expensive considering my entire mastery can farm like crazy. For a new player though, I imagine they'd need to be told that. 10 -> 15 can be a bit of a struggle if you don't know about seals for quick levels too.