Affiliate Marketing Secrets

I’m opening a website soon which lets users sign up and manage polls. Not going to go far into detail but the question is, how big do you have to be to give yourself some pay ($100-200 a month). I know it all depends on your site traffic and niche and such but I’m not aiming for anything as successful as formspring/twitter/facebook and I’m wondering how hard it will be to make this worth my time. I’m spending $800 on the site development and then will be working on bringing users to my website. I figure if I have 500 active members I’d get at least 50 page views from them and their friends every week, giving me 25000 page views a week and 100,000 a month.. Even at a lot CPM this would be a decent profit for me, right? I know I cant guarantee page views but how terrible does this idea sound? Thanks! 😀 open to ANY and ALL suggestions/comments.