I'm not an expert, but from what I've learned, pocket watches are collectible, but don't command the prices that wrist watches do. I believe the maker contributes more to value than the age; with Waltham, Hamilton, and Elgin kinda leading the pack. The big 'railroad' watches are actively collected.
What's a real shame is that whenever the price of gold goes up, more of the existing inventory of fine pocket watches get melted down. That's why there's so many Waltham and Hamilton movements on Ebay, without cases.
I also know that there's a cadre of esoteric collectors who chase after various mechanical movements, based on criteria I couldn't begin to understand. And in some cases, I think this ties into regions in Europe who's cottage industries built identifiable movements.
Also, I'm told that the high-end European pocket watches like Patek are not sought after by collectors, so much, but are valuable based on who made them.
This little bit that I've learned came from two watchmakers who cleaned and serviced several pocket watches that I inherited. One was a watchmaker/collector. The other was an ancient ol' skool guy who's watchmaking skills enabled he (and his mom and dad) to survive the Auschwitz concentration camp. One of the extremely rare cases where an entire family survived. Fascinating man.
Here's some pix of my inherited watches.
