bought per meter, etc. I keep them sorted by colour in boxes from a Dutch budget store (1€/each). It's a bit messy but it works fine for me .
I have my ribbon on rolls seperatly in this box from Really Usefull Boxes (http://www.reallyusefulproducts.co.uk/). I must admit the bigger rolls don't fit in, but I don't have a lot of these so I keep them somewhere else.