Well, if you do make your own, you can control its spicyness...
And it is really, really easy. Even a person with two left hands (e.g. me) was easily able to make it.
OK, my pragmatism (huh? what? Korean red pepper? Don't have that, so regular chili flakes should do) meant that for my first batch, it was really spicy, although I had been going for a "medium spicy" taste. (Note to self: Obviously Chili flakes are more spicy than Korean pepper paste with unpronouncable name, next time reduce amount)