Do you ever buy those little travel sizes of soap, shampoo, toothpaste, deodorant, hair spray, and other toiletries? Maybe there is something else you buy in travel size. Trial size versions can come in Handy too, if you can get them at discounted prices. I've found that it's actually cheaper to either fill containers you already have or to buy reusable travel size containers and fill those from the regular sized products. This might not work for everything, but it works for a lot of things. As an example, a tiny, travel size bottle of shampoo can often cost as much as regular size bottle. I just don't think it's worth it. Maybe, if the trip were an emergency or something, I'd grab these, but otherwise, I'll fill my own usually.
I will occasionally buy travel size body wash and toothpaste because they are easier to travel with, but I still usually bring my full-sized bottle of shampoo and conditioner when I travel. Unless I'm going for only one or two nights, the travel size containers don't normally hold enough to justify buying them.
I do. In fact, it's the only way to ensure my bag will not be as heavy as a huge boulder. I buy small sachets of lotion, shampoo with conditioner, facial wash (because hotels don't provide facial wash, usually), deodorant, soap and insect repellent. They all fit inside a palm-sized pouch and can be stuffed anywhere in my bag.