Rose hips are fine, just know that some chinchillas don't like the whole ones because there are fibers inside that can be irritating. Ours likes them but not all do.

You can get a pound of organic, crushed, dried rosehips for around $15 which will last a long time and don't have the annoying fibers.

Chins will pee out the excess vitamin C so don't be alarmed if the pee turns a bit reddish. And they still need to be given in moderation, like any other treat.

https://www.amazon.com/gp/product/B003AYEHL6/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1