IMO you will find very hard affiliates to advertise on a site unless you have good traffic and stats to prove it.
Think like this:
– you are asking the affiliates a fee that is higher then what you would earn as an affiliate yourself(it doesn’t make sense to sell your space for less money that you would earn yourself as affiliate plus the playerbase and recurring revenue you will earn in long term)
There are not big differences of what you can get as a new affiliate and well established ones if you personally aproach affiliate managers. You should be able to get good deals for your top spots.