Knives
Feel free to buy your knives from the dollar store if you only need ones that would not be all that useful. They will do fine for the odd camping trip, but you can save yourself a great deal of frustration by investing in good knives instead. Trust us, you will be relieved that you did this instead.
Earbuds, Headphones
We can see the appeal of those headphones that only go for a buck or two. However, you should know that they have poor sound more often than not. You should just get a good pair for $10 to $20 at a major retailer. These things will last you much longer than the cheap ones!