1. Contraception. This may seem weird, and no-one had even thought about it, until suddenly there were small pockets of people bartering with others for all sorts of types of contraception. When you're stuck on a ship, in a completely different Universe, with no chance of getting home to renew your library books or catch up on your favourite TV shows, there's only really one thing you can do to keep yourself amused. And if you don't want the population of the ship to double, you need contraception. And they had run out!
2. Chocolate. The boys wanted it and they girls were adamant that they needed it. And there was none left for anyone. They had managed to synthesise something that was close to it but it wasn't the same. Some people only really wanted to get home just to have a good bar of chocolate.
3. All sorts of hygienic supplies. Things like toothpaste and shampoo (and a couple of other things that no-one really wanted to talk about) ran out very quickly from what little supplies they had brought. This was something else that was being synthesised by all the scientists but, again, it wasn't the same. Still, if it worked, no-one was going to complain too much. At least they had something.
4. Paper and Ink. This may not seem essential but when TJ was telling everyone that it would be a good idea to keep diaries of their thoughts and feelings so they could stay sane, it was pretty much as essential as it got. And there supplies quickly ran out. Thank heavens that there was enough Kino's to go round and they could start doing video logs instead.
5. Hope. This was probably the most important thing to have, and the crew of the destiny were running out quick. No-one had any hope anymore that they could go home. They all learned to make do with the nice planets they could visit and pretend everything was ok. They created new little families amongst themselves but lost all hope of seeing their real ones in person again.