Brian Sacawa, Author and Creative Director for He Spoke Style, an online magazine for men, shared his perspective on the collar bar, which I found both interesting and helpful.
If you don't know what a collar bar is, it's the metal contraption that pulls your shirt collar together and gently lifts the head of your neck tie. While it's not often seen today, it still makes the rounds in magazines and television, leaving one to assume the wearer of a collar bar is stylish and earning way more than we could hope to make in our lifetime.
This image from Gentlemen's Gazette, shows four styles that can be purchased for $30. These are also available at Macy's, Nordstrom and the like. Of course, if you're looking for something vintage-looking, you could get on Etsy.
To prevent your shirt from tearing over time, your best bet is to invest in a shirt that comes predisposed with collar bar holes that are stitched for reinforcement. Otherwise, the alternative is to use collar bars for only a couple shirts and leave the other shirts untouched. There are clip-on tie bars too that would work if you're worried about damaging your $300 Calvin Klein.
Wearing a collar bar should be worn less than "sometimes" because the impact of the power or sophistication can get either cartoonish over time or lose its impact when it's really needed.