Cost v. Need? That's really a tough one to call. I work from an armored truck every day, but I've never been robbed. The one time I thought things were going to go bad, I was very, very glad to have some basic proficiency with my pistol. Like they say, it's better to have it and not need it than need it and not have it!
So far, my only formal training has been the SC Qual Course, NC Qual Course, and Suarez Intl's Close Range Gunfighting class. The latter was a real eye-opener and I would highly recommend you attend when Gabe comes to your area. His presentation skills are worth the money, and he's very good with the pistol.
What I especially liked is that he didn't focus on times or accuracy. Rather, he gives you the basic steps, what you need to do in a gunfight and why you need to do them, and then expects you to practice for speed and accuracy on your own time.
After attending Gabe's class, I now see just how much there is for me to learn about saving my life.....and I'm anxious to learn more. And, I think a better question to ask yourself isn't when you might possibly need it, but what will you do if someone else (husband, wife, mother, daughter) dies because you didn't have it?! That's the one thing that weighs on my mind most.
Money can be earned tomorrow. Train and enjoy.