There are several places in Koreatown that specialize in live fish (such as Halibut and Sea Urchin), and also serve sushi, hwe dup bap (sushi rice), fish soups, grilled fish etc such as A-Won, 8th Street Live Fish, Hwal A Kwan Jang etc., but let's try Wassada.
Since the fish really is "live" you may - if you order octopus or uni - see it moving around, or in the case of octopus clinging on inside your mouth for dear life but most of the dishes should instead behave, lie still and just be very fresh. Still, this isn't the place if you are squeamish or a picky eater. When you order something that sounds simple you may end up with lots of bonus courses of unusual seafood so this is the place if you have an adventurous palate, and not the place if otherwise.
Prices are high as you might imagine, just as it would be for any place that focuses primarily on Seafood. Expect to spend roughly $50 per person but bring more money to be safe!
The other thing about Korean sushi is it can often be served crunchy (semi-frozen), this doesn't mean they hate you and therefore didn't take time to warm it up, it just is the style Koreans prefer.
As for me, I wouldn't mind trying the live octopus but I'm personally more looking forward to live uni. In any case we will certainly order a live halibut combo and anything else that looks interesting on the menu.
Family style dining - which means all food costs are shared regardless of what you decide to eat - or can't eat, but can only manage to stare at - in which case maybe at least you'll get new ideas to try out in a live octopus circus act. Drinks? There you are on your own and we don't share drink costs.