What is the website to look at list of profile backgrounds and sort by economy?

I am trying to find out what is the list of most expensive profile backgrounds. Someone posted a link to the picture and people said "wow that is expensive" yet I only see the link (a picture) but no way of knowing it is expensive.

example: http://steamcommunity-a.akamaihd.net/economy/image/fWFc82js0fmoRAP-qOIPu5THSWqfSmTELLqcUywUlj3Hz8JQD_k62zmnzAEbeQUdVBitsTVCj831QvuYDe0T1IhlssIGiXk_xFgubefhNmUyJAfGWKJaXaJtpArpXX5j6ZZlBI7lpLpfKw7qvNDALepsZyYwSncA (how do I find out if this background is expensive as some people said?)

Thanks for reading