Even the production year of a perfume, let alone how rare it is, can make it more valuable. Some perfumes have what we call batch issues (if you are wondering what that means, read my Batches & Reformulation entry in the Terminology section), and for example, let's say a perfume was reformulated in 2024. In that case, bottles produced in 2024 or earlier can suddenly become much more valuable. As you can understand, if even the production year of the same perfume can be a factor in determining its value, just imagine how valuable a perfume can become when it is also rare and produced in limited numbers.