Assuming you've got a decent affiliate review site that's converting around 1.5%, but you know nothing at all about PPC, how much would you expect a noob to put out in order to learn the ropes and start pulling a profit?
I'm not sure if I understand what you exactly mean, but here is what I understood. PPC stands for pay per click, you simply place ad network ads on your site and when someone clicks on the ads you earn revenue for that. The profit from ppc can range based on your site niche and traffic.
You're going to learn about your ability to convert VERY quickly when you start paying per click. Once you've got an AdWords/Yahoo campaign running, you will likely find a different conversion rate than your organic traffic. It might be higher-- as visitors who click on sponsored links are more likely to buy than organic visitors. If you've established a conversion rate from your organic traffic, take a look at what keywords are converting the best and try to purchase those with PPC. Note that the importance now will be working your hardest to advertise ONLY to buyers and not putting your PPC ads in front of anyone else. The goal is relevancy, the art is choosing the right keywords intended for buyers, and you'll see your conversion rates increase and your spend on PPC hit a comfort zone.
It's all depend on various aspect: how you choose your keyword in PPC, how targeted your PPC campaign, how you track your campaign and how you cut off a losing campaign. test small amount first, see if until 50-100 click and no convert(or even convert and losing money), toast it away. you can download free ebook teaching you on PPC to CPA offer in my signature. you can just learn on PPC part, how you can brainstorm and use tools to get targeted keywords.
With AdWords, there is a $5.00us setup and the rest is for the campaigns. We have run campaigns for $1.00 per day and up to $13,500 per day. Just use the "Position Settings" to keep the cost down.
You can actually try JoomlaAds they currently offer free $5.00 for advertisers. I signed up with them and I'm waiting for the $5.00 found to be added to my account.