There are a few that have lasted, but I've never really seen any of them as a positive when it comes to cost/benefit. The sky is the limit on price, and none of them are really what I'd call "affordable". But more than that, you have exactly zero confidentiality. The machinery, the noise, the staff; you'd have to spend a few million dollars importing labor, keeping them totally isolated and unaware of their location, etc. if you wanted to make sure no one knew where it was.

Also, most of the commercial shelters I've seen suffer from serious deign problems. For example, many of them have a single entrance, and it opens outward; depending on what you're planning for, you are one piece of heavy debris on that door away from slowly starving to death.

For my money, you're far better off reading "Nuclear War Survival Skills" by Kresson Kearny, learning what sorts of flaws are common in shelter designs, and then maybe tackling it yourself or with a local contractor. If you need to hire in labor, keep the labor force small and see if you can manage to keep the real purpose a secret; for example, have them build most of it as a "root cellar", then add in the details later yourself that would betray its real function.