The first two are dead basic, the white one is a silky material and the black is just plastic, I have loads of these because when I have my hair up I separate my fringe and the hair pulled back.
This blue one and the flower one below are my two favourite at the moment, I think they are really sweet (especially the flower).
The blue one is from accessorize for £4. I've check their website and its no longer there so that might have been discontinued now, but there are some similar ones that are cute.
£3.50, also from accessorize ( suprise suprise :D )
This was still on their website.
And this one is from Peacocks, it looks brown on this picture but its actually black. For £2 its as good as you could expect, hanging a bit loosely.
I like wearing these because if your having a bad hair day and you've just put your hair up it can still look really nice and more styled if you put one of these in.