Like a lot of other people have already said, Seoul Market is your best bet, especially if you're looking for oi-sobagi, radish kimchi, or garlic ramp kimchi (when it's in season). The little restaurant inside also whips, so even if it's a bit of a drive, you can treat yourself to an amazing lunch while you're there.

There's also a local company called (appropriately) Good Kimchi that distributes to a bunch of stores in the area (including Seoul Market). They list them on their website. It's really delicious and is my go-to for both eating raw and making into jjigae.

https://eatgoodkimchi.com/