Cryptocurrency exchange (similar to wex.nz/bittrex)

I am looking to create a website very similar to [login to view URL] or bittrex. It is a cryptocurrency exchange which will work together with other exchanges (meaning it can trade off of other exchanges if possible). The exchange will be visible without login in (like [login to view URL]) however you will need to create an account to start trading. I do not know the exact pricing of this, but I would appreciate it if you would could leave an honest cost.