Computers change everything. You could even have the price increase on each sale, from multiple sales venues (if they were linked to the main site), if you wanted to.
Ansel had the best solution...no new prints made from old negatives after a set date, like your 70th birthday for example. This way, if you've managed to cultivate a money-lusting herd of collectors/investors during your career, there should be quite the frenzy of orders just before you turn 70. I think Ansel bowed out with over $1,000,000 in sales in his last year...and that was the early 1980's wasn't it? Call it a retirement plan