add download bw prices to 'host -v' cmd

Wanted to be able to have a broad overview of the download prices on the network. Interstingly enough, there are a lot of renters offering downloads at below 500 SC / TB / Mo, meaning downloads are actually super cheap on our network. If we were optimizing for download price, we'd be able to hit $0.20 / TB, which is something a few potential large users have asked for.

Exciting to see how crazy much flexibility there is on the network.