Selling ad spots directly to other developers? How much would you pay?

I have a pretty popular app on the market. While I don’t want to out the name just yet, I can tell you it gets around 500-600 downloads a day (with over 150k+ downloads) and it is an app that is similar to AppBrain. I am thinking about creating a section in my app called ‘Sponsored Apps’ where I can display a list of apps and games from other devs. I know a lot of companies charge devs per install but I’d rather just charge one small fee and let the app be present for a specified amount of time. I use to sell advertising to other devs but that would be for the featured section of my app where it is front and center. I stopped doing that because I didn’t have enough time to manage all that. I did recall the CTR being pretty high on those featured pages. 4000 clicks within a few weeks (if I remember correctly). I use to measure the clicks with bitly.

I’m not here to necessarily sell you anything. I just want to know how much a dev would pay to be in a sponsored category. In comparison, I use to charge about $75-100 a month just to be featured. I’d rather have a lower cost with high volume to offset the difference for the sponsored category. Do you think it would benefit you? Would this be something that would interest another dev? I was thinking about charging on a weekly basis. Has anyone created a similar section in their app?

Rather think of it like this:

If you app was pushing 100 billion adverts per month, would you still charge a small fixed fee for access to all those people ? If the answer is ‘no’, then you probably need to think about things again.

I think you could check out Chartboost, they provide a direct dev-2-dev exchange service but you need to have some scale, ie. DAUs.