The main components of KY are water and glycerin (glycerine/glycerol) and both of these are good for thirsty hair. Water is of course the ultimate moisturiser but locking it in is the main activity that most naturals want to perfect. Glycerin is a perfect tool for this because
1. It is hygroscopic - meaning it bonds to and retains water. (Hygro meaning 'moisture' and scopic in this case meaning 'seeking' - therefore moisture seeking) (Griffin, W. C. et al Journal of the Society of Cosmetic Scientists, 1952)
2. It is a humectant (because of no 1) and therefore can be used to stabilise the water/moisture content in products (perhaps as in KY) (Journal of the Society of Cosmetic Scientists,pg 19, 1958)
3. It makes hair softer (Journal of the Society of Cosmetic Scientists pg 251-263 1989)
4. For natural African hair, it prevents premature failure of hair - and therefore, premature breakage of hair when the hair is under stress (combing/stretching/pulling). However if your hair is relaxed, there is no such benefit (Journal of the Society of Cosmetic Scientists pg 39-52 1985)
5. It offers some thermal protection to hair, preventing cracking of the cuticle on exposure to heat (Journal of the Society of Cosmetic Scientists pg 141-153, 1998)
I am guessing if you were thinking about KY, a cheaper option could be buying some glycerin and mixing it up with water to get a consistency that you like.Some words of caution though is that getting the water to glycerin ratio for your hair is probably easier said than done. There are well reported issues with some users saying it is too sticky or drying (not!!). Glycerin does have to be mixed with water before you use it as if you do happen to get pure glycerol, it will absorb moisture from the air and your hair if applied directly.
However, provided you add some water to it and you should be ok. It may take some experimenting to get the right level for you.