It's very minimal so I wouldn't worry about bandwidth. I'm running a VPS and I'm way below my allocated bandwidth limit. I also recommend a VPS if you don't have access to an always on machine; and even then if a VPS allows for remote management. As stated in my earlier review, there's a strange sense of wonder watching the bot work.
I have rented a VPS from 1and1 for 5 USD/mo with a year long contract. I don't regret it. You can use my referral to buy one for yourself: https://www.1and1.com/vps-hosting-packages?ac=OM.US.USf11K357093T7073a&kwk=537884072
When I get my hands on a Gunbot licence, I'll try installing it on the VPS.