True! But collectors (who are the target audience for any type of limited edition, really) are not only paying lots of dollars for the
quality of the production (high production costs) but also for the
quantity (small print run). Resale value has nothing to do with it because collectors don't buy books with the sole purpose of reselling. Collectors are prepared to pay a certain price for the lettered edition because it's well-crafted but also because there are only a certain number of copies issued. When you preorder a book and decide to hand over x-hundred bucks for a book that (so you are assured) only 26 people will have in their collection, it's quite dissappointing when you subsequently hear that the size of the print run will be increased. Sure, the production quality remains the same but the limitation (which is an important reason for people to dish out extra cash for a lettered edition) is altered. It seems logical to me that this should be reflected in the issue price.
Of course, I'm not really serious about decreasing the price with 50% but I think there should be some kind of compensation. Especially since the size of the print run was increased as a sort of afterthought. Otherwise people could have decided not to take out their wallet in the first place, when weighing the issue price against a limitation of 52 instead of 26 copies.
Sometimes when publishers increase the print run they say it's because they 'want to give more people/collectors the opportunity to buy the numbered or lettered or whatever edition' but I think that's nonsense. If you want a lot of people to buy a book, then don't publish a limited edition. It's called limited for a reason!