only had a quick look but could only find one and it was £1600. I found a few with dual 2.5/10gbps at a relatively reasonable price.
Do you move that much data? fastest BB in the UK as far as I am aware is 1gbps so no benefit going any higher than gigabit lan and even then to justify it soley for the internet you would need multiple machines hardwired and downloading a lot imo. Only benefit of these types of speed is if you are in a data centre or moving massive files across the network all day every day