An average doctor's visit costs about US$3. An average prescription costs about $4. Can't beat that. Prices go up for specialists and special medicines. My allergy medicines cost a total of about $25 for a six week supply, but that's for three different brand name drugs. In the USA, that would easily cost over $100 even with insurance.
The downside of the the government insurance is that it's great for the small, normal stuff, but not so good for the really expensive stuff. Korea has a booming market in supplementary insurance for large medical costs. However, for about $70 a month, our whole family has basic insurance. That would be a massive improvement over the US system - almost beyond the power of adjectives to describe.
And, in case you're concerned about the quality of care, my layman's estimate is that the quality is about 90% as good as in the USA. And those deficiencies don't stem from the system itself, but rather from the fact that 50 years ago Korea was one of the poorest nations on earth. It's still catching up in some areas. For a more thorough look at Korea's health care system, check out this excellent explanation on Ask A Korean.