tea shops in Seoul

Can anyone recommend a nice tea shop in Seoul? I'll visit there next week (April 8 or so) and I'd love to try out some interesting tea there, and bring some back (to Thailand). Let me clarify.

I'm a tea enthusiast / blogger, so although I drink all kinds of tea I love trying different kinds, and prefer black teas and darker (more oxidized) oolongs over green tea. I'd also love to try dok cha, Korean compressed tea, in my understanding a loose comparison to Chinese pu'er, but quite different.

Google knows of a few shops (Yetchajip, O'sulloc, and the Beautiful Tea Museum), all in Insadong, but I keep reading there are hole-in-the-wall shops that are probably just what I'm looking for; a good place to get interesting teas at good prices, to stock up a bit.