Facebook (before I got Banned) $100 a day
Bing Ads $200 a day
Autoresonder $30 a month
When I start a new affiliate offer I spend at least $300 to test it, usually $500. The reason is because if it does not convert right away, I change my ads and test again. If still nothing I change my landing page..sometimes up to 3-4 times to test that.
I change my landing page and ads and monitor results...if after $300-$500 I see no positive ROI I move on. either it does not convert or it takes way to much work to convert a searcher into a buyer.
If I am seeing at least a 50% ROI I play with it more to get that up as high as I can
If I see about %100 ROI or more I generally just leave it and start the next project, monitoring the site a few minutes a day...
But with all this said it does not matter what I spend, or anyone else for that mattter...all that matters is you dont spend more than you can afford to lose!
Best of luck
Ryan