I wish I had used more of specific perfumes before they were either discontinued or turned. As I found out to my disadvantage, ebay buys often are already turned. I keep reading these stories of people who buy or own 20 year old perfume (in the highest concentration, like pure perfume or EdP) and these are perfectly good; it never happened to me.
Like a PP, I very much miss Fendi by Fendi and Ultima II, and some others which were reformulated.
Aside from the shops that create dupes, which sometimes are mentioned on here, I can recommend looking at sites like fragrantica, which list the main notes and at the bottom of the site have suggestions for similar brands. Unfortunately often these are more expensive, but sometimes one is lucky and finds a cheaper alternative.
The storage of make-up had similarly mixed results for me. Some items keep well, such as eyeshadows, but anything with oil in it, like lipstick or liners, tended to turn rancid after a couple of years, even while being kept as cold as possible outside a fridge; so as much as I'd like to, I do not buy extra anymore.
The beauty blog Temptalia has a very extensive swatch database, where it is possible to compare products and look for replacements of discontinued products. Even characteristics like texture or shine are considered.
@Ginmonkeyagain
Was your Bourjois eyeshadow of the baked variant - the ones with a dome shape? In case you manage to find the replacements, baked shadows and blushes tend to break more easily I found. I wrap my make up in bubble wrap for travel, though I didn't try it with baked products yet, but it did help with regular pressed shadows.