Even with the best sales guy it's very hard to sell when there is no market appetite. Sounds like the demand is there, media never needs to 'run out of spots'.
Its a highly valuable market niche and you are possibly underpricing.
I suggest you increase your sponsorship prices drastically.
We optimised the price in a way that we are able to sell out. It was also the maximum in revenue we could have reached so I think we did well in that sense.
The key here, in running a media business, is how do you go about building enough products that will keep you running through out the year - when there are no events (which for us where the biggest source of revenue).
I think this question will also remain a question to answer for the future, no matter how ArcticStartup will run.