Like anything else it depends upon how much you'll use it. A small single burner stovetop grill only costs in the neighbourhood of 30$, which is no different than a similar pan. If you'd use it that's well worth it. A nice two burner stovetop grill might cost 140$ and you'd want to have a need for it before you paid that much.

You can grill soup. Other ways to prepare soup are on the stovetop, in a crockpot, and even in the oven.

A stovetop grill is easier to use than an outdoor one. There is little set up, less clean up and you are not subject to the outdoor elements while cooking. If you prefer the taste of outdoor grilled food, though, the convenience factors may not even be an issue for you.

From what I have researched and can find online, it seems that a Korean BBQ grill is something that is used indoors on a stovetop as opposed to a regular outdoor BBQ.

You can bake brats, broil them, or cook them on the stovetop in a skillet with a little water.