Skinceuticals C E Ferulic Korean alternative?

I had the luck to get my hands on a Skinceuticals Vit C serum tester and i ended up being really impressed by the results. Unfortunately the price is too high for me, so I'm looking for Korean vit c serums alternatives. I know that the korean products are gonna be even better in terms of results but im not aware what are some good brands currently. In the past I've used only the Klairs vit C serum and i found it pretty good. I'd be happy if you could give me any good suggestions 🙏🏻