I've used the same hair ties for the longest time. I don't think I can remember the last time I bought a pack of ties. I've had one for like three years I think and whilst it does wonders it's old. I have search the stores for a pack of the one I own now but that search has been useless, they are nowhere to be found! what a bummer.
Well since I could not find them I decided to make my own with some elastic that I has laying around. I cut the elastic into 10" sections first. I only made three because they usually last forever for me. Once you cut your first section you folded in half and tie a knot and ta da!! you just made yourself some hair ties!! I made mine white because like I said I had white elastic but you can use any other color elastic. I think that black is the most convenient one.