1

Planning to stay in South Korea for two weeks. Would be nice to have GSM prepay card for data transfer.

Found two providers:

EG sim
http://www.egsimcard.co.kr/eng/buy-eg-sim-card/online/buy-egsimcard.asp
Cost 5GB = 60000 KRW

KT
http://roaming.kt.com/rental/eng/product/sim.asp
Cost unlimited data 10 days - 38,500 won 

Which one has better coverage and more reliable. What are hidden costs? Where to buy?

There are more providers?