A classic chypre calls for oakmoss, labdanum, patchouli, and bergamot among its ingredients. You’ll know it when you smell it. (I’m still learning.)
In life, as in perfumery, sometimes you can’t get all the ingredients you need to follow a conventional recipe. Then what? You might try substituting Veramoss for oakmoss (I haven’t thus far). Or you might try innovating and coming up with something completely different.
The real question is whether you’re after the ingredient in and of itself, or the totality of the effect that can be hard—but, note: not impossible—to recreate without said ingredient.
I’ve had some olfactory disasters using oakmoss. It can’t be above a certain concentration, and it doesn’t play well with some other aromas. Having a vial of oakmoss doth hardly guarantee being able to make anything close to a chypre.
(I wasn’t even trying to make a chypre at the time, but something else entirely… for which oakmoss may not have been appropriate as a featured character.)
By deduction, it must then be the effect that is worth pursuing. In that case, we might be in luck, as there are thousands of ingredients available for choosing a few good ones to craft something beautiful.
Then there’s the part that involves work, and learning, and iteration, and observation, and thinking, and patience……
In life, as in perfumery.