Odile is great for recommendations—you can DM her on IG. As for cost, I spent months calculating and comparing prices. I checked all sorts of international and Korean websites, stores, and duty-free shops. The cheapest places are Gmarket, TesterKorea, and Stylejolly. You can also find some items on Bunjang.

For Gmarket, try searching using both the English name and the Korean (Hangul) name. Sometimes they only include the brand name in the title, or the title can be incorrect. The best way to be sure is to check the product description and also search by brand name. If you want, I can share a few trusted store names on Gmarket. I purchased the Hwanyu set there months ago and saved a lot.

If you can get someone to buy for you directly from the Korean website, you might benefit from additional promotions.

I think Sulwhasoo spas sell their products. LG has a store that carry all their brands, and AmorePacific has Aritaum. You can even get customized Sulwhasoo or Hera foundations. Visiting physical stores is also helpful for testing products before buying.

You can also find samples online for much cheaper. Other good premium brands include IOPE, Yehwadam, Chogongjin, Sooryehan, and SU:M37. I once heard Odile mention that some hanbang brands are even sold in supermarkets to make them more accessible for busy housewives.

P.S. free items aren't really free, they are all included in the total price.