For good, fast, cheap, hot ddukbokki, I've always been happy with the stuff at the Chicago Food Corp. And Dddukbokki doesn't come with pieces of fish, rather fish cakes. It's also pretty easy to make at home, as thetrob says. For my vegetarian husband, I make it without fishcakes and extra veggies. In the frozen packets at the groceries, I kind of like the new fun shapes I've been seeing lately. There's one shape that looks like little snowmen. Also you can sometimes find brown rice cakes as well, if you want to be a bit healthier.
I like this Korean cooking blog for some recipes, and her recipe for ddukbokki is pretty good.
http://www.maangchi.com/recipe/ddukbokkieChicago Food Corp. (Joong Boo Market)
3333 N. Kimball Ave.
Chicago, IL
(773) 478-5566