Here is a simple recipe for homemade hair spray. All you need is:
Chop the lemon (or an orange for dry hair). Place in a pot with the water and boil until half of the initial amount remains. Cool, strain, and place in a spray bottle. Store in the refrigerator.
If it is too sticky, add more water. You can add the rubbing alcohol as a preservative and then the spray can be stored for up to two weeks unrefrigerated.