This is a must stop by place for me whenever i'm in Seoul.  Definetly because of FTISLAND.  Plus the staffs are normally quite friendly and alway gave extra posters, catalogs etc.

 

For convenience sake, the one at Lotte World department store is the most easily located store.  But I notice this particular store normally doesn't have any discount or promotion when other outlets have.  The last time I went there in Sept 2012, they even ran out of posters.

 

So I would suggest going to those normal outlets that are outside, not so much for tourist but for locals.  They tend to have sales/discount and the Ahjuma are always so nice to give me extra paper bags and posters.  I ended up with 9 posters for the 2012 Fall/Winter..Haha..

 

But a pity the latest catalogs and paper bags are not yet printed.. :(

 

The one I alway go to is at 까치산점 (kkachisan subway station)  Its inside 까치산시장 (kkachisan market).