Is it rare, or just difficult to catch? The way they talk about it implies the latter. It wasn't 'this is a rare species' as much as 'you don't often find it on the market', and the party didn't seem surprised that he'd found one, only that he'd been able to catch it.
Just on the 'tl note' at the end of the chapter;
"A journey of a thousand miles begins with a single step" is a reasonably well known idiom in English. The way it's worded on that page is a little odd, but English audiences would have understood just fine.