How much is the Iphone case that charges your phone?

I don't know if the case is for 3gs but if it is what are the prices

About $15 at the http://www.onecase.co.uk/iphone-cases/iphone-3g-3gs-cases.html

I bought my cath kidston iphone 3gs case from a website www.case2case.net. The price is only $23.99, i even got a special discount and free shipping service.
give you a direct link here
http://www.case2case.net/cath-kidston-case-for-iphone-3g-3gs-flowers-soft-shell.html