Non-typical Advertising Agencies/Brokers?

First of all, apologies if this is not the correct forum for this...

I run an internet radio station, geared primarily towards gamers, which is has become fairly well established within certain niches over the past 2 years.

We recently made the decision to add in-stream advertising to the station, and have secured our first major games publishing client.

While we do have a lot of strong connections with gaming companies in our niche (MMORPGs); these are mainly PR based, and while they come through for arranging interviews and coverage, sorting out advertising is a different kettle of fish.

Considering approach the "big-boys" of gaming such as EA, Blizzard etc is a daunting concept, and would be taking a step out of our league, as such i've been contemplating enlisting the assistance of an representative agency.

Before taking this further, however, I wanted to see whether I could get any advice from you guys as to whether there are any particular agencies you have had experience with and would recommend, who could approach potential clients and broker deals on our behalf.

Our main priority is maintaining quality and integrity with the ads we play. A lot of what we do involved constant interaction with our listeners in the communities they are involved in - and if ads for things such as car loans etc started popping up in our stream, the listener counts would drop.

I'm also curious as to how these sort of arrangements work... ie do these people charge a set fee for their services? Or do they just take a cut of the revenue gained through advertising? We'd really be needing someone who would listen to our needs and tailor their approach according to the technical specifications of how ads actually fit into our stream.

Any help or advice I can get would be greatly appreciated.

Cheers

 

No suggestions?