Japanese ex series is pretty similar to most of the subsequent Japanese releases in that there really isn’t a big price difference between 1st ed and unlimited. In many cases the 1st ed print run is the most significant and the majority of cards are 1ed. There are some sets where the difference is significant, Clash of the Blue Sky has a much more significant unlimited run and Offense and Defense of the Furthest Ends (Dragon Frontiers) has it about split in my experience. I think there’s a couple more sprinkled in there, Undone Seal 1ed is sometimes a pain to come by but most of the Rocket Gang Strikes Back cards I’ve seen are 1ed.
In terms of price difference, it is usually negligible. The only price differences between 1ed and unlimited are likely due to issues outside of the stamp, for example Japanese Dragon Frontiers has abhorrent centering and print line issues making 10s very hard to achieve compared to regular Japanese cards. The unlimited run has better (although still very bad) centering. As such I’d expect to pay a premium for the few 1st edition 10s that do exist out there.