Does Anyone Look For PCGS "Rattlers"?

There's no way to know the counts you are requesting. There isn't a system in place to track them. It's anybody's guess at this point.

They do seem to bring a premium because there is a perception that they were undergraded and would re-holder at higher grades. This may have been true a few years ago, but I personally believe most of those have been resubmitted. The majority of the remainder "are what they are" and don't deserve a premium price tag.

I do look at them and evaluate the coin, not the holder. If I were to see an undergraded coin, I would try to acquire it.