I was given the Searzall propane torch attachment as a Christmas gift and have found that it produces a much more professional sear than does a cast iron skillet or gas grill.
SEARZALL Stainless Steel Culinary Torch Attachment
It was more money ($70) than I wanted to pay for something like this, but if you have family members that will chip in and get it for you, then make sure to ask for it for your next birthday or holiday.
I like it because it gives a much more even sear than a cast iron pan, and it doesn't change the doneness the way trying to reverse sear on the grill often does, especially if your gas grill doesn't have a special sear feature.
I also like it because you can easily sear the edges of a nice, thick steak, something the pan and grill don't do without a lot of extra work.
It takes 1-2 minutes per steak, so it isn't instant. I used it on some sous vide steaks which, obviously, have no sear whatsoever, and it took 2-3 minutes per steak. For steaks done in a more conventional manner, it takes only about a minute per steak to "kick it up a notch." I really like the fact that you can get a sear that has a crust, something I remember from my few visits to Kansas City and NYC high-end steak houses.