How much do butterfly knives sell for in stores?

I just got a butterfly knife and I was just wondering how much they sell for in the stores because I might sell it. It is just a regular silver blade with a black handle with holes in it.|||I sell them for $6.99|||Price would depend on the quality of the materials and the condition of the knife. If it's just a regular nothing special knife then don't expect much at all because if it's even legal to have a buyer would not pay a lot for it.|||I don't know, it would depend on the quality and uniqueness of the knife. Note that in many states, butterfly knives are illegal.