Something else to consider about triple threads beyond just the price. If you were to break down a triple thread into just one thread, the TPI is far less than a single thread. This is because you need room for 2 more threads. It's like a spiral stair case...a triple thread stair case is far steeper for you to walk up than the single lead. Because of this, a triple thread is going to screw together faster. But...on the negative side, this is also why triple threads do not hold tight very well. In my opinion, I would rather make 2 extra twists on a pen cap and have the cap stay one, than have it come loose in my pocket, the pen fall down and get ink on my shirt or fall out and land on the ground breaking the nib. I prefer single start threads.
Negative #2 about triple threads, is that you never know where the cap is going to start it's threading. A plain wood or plastic pen..this won't matter, but if you have a nice segmented pen, or some real cool grain on a pen, or some images that should line up a certain way on a pen...well you can't count on that happening every time you cap a triple thread pen. With a single thread pen, it always caps the same.
just a few things to consider before you dole out the big money.