Must-try K-beauty treatments during a Seoul trip?

I am visiting Seoul for 2 weeks and want to experience authentic Korean beauty treatments that I cannot easily get in my home country. What are the must-try treatments in Korean dermatology clinics or beauty centers? I have heard about things like aqua peel, LED therapy, and various "glow" facials. What treatments would give me the best results in a short time? I do not want anything with significant downtime since I will be sightseeing. Budget is around 500,000-1,000,000 won for skincare treatments. Where do locals actually go for these treatments vs. tourist traps?