1.) Untrusted + INACTIVE Profile
2.) No Escrow
3.) Site is still Under Development
4.) High Number of Quality Posts = Very Low Payments
5.) Not Convincing ANN

I guess, OP should consider this points. Before asking too much. How can they agree on advertising your site? How can they trust you, even if you, the Manager isn't that active here. So many gaps on your post history.

With that kind of payment, I think it's better to find users who will advertise your site for free rather than making this offer. And I'd rather advertise Charity works than this. You might want now considering your rates having it much likely slightly increased. For ideas, there number of campaigns here. Or maybe as for the last thing, you can just make it atleast 10 for mininum constructive post count.