If you are willing to learn the outlines of what is publicly available you could start with what the Mormon Church is sharing for free on familysearch.com.
https://www.familysearch.org/en/wiki/Korean_Genealogy
Americans love genealogy. My brother-in-law is Korean. He immigrated with his family at a young age. My mom was able to look up background on the founder of his clan on the Internet based on last name only.
If you Google carefully, I'm sure you can find a reputable service.
It will save you money if you gather as much information as you can on your end. Names of ancestral villages, immigration paperwork, etc.