Are ads profitable for your Internet startup? How much?

I think he was asking about displaying ads on his site - not buying ads.

I've tested a lot of services on several different sites and Adsense has consistently performed the best.

I have a range of sites earnings anywhere from $0.50 CPM to $50 CPM using Adsense.

It really depends on the type of site you run. Sometimes it's not even worth placing ads if your traffic or quality of visitor is low. You may do better with lead generation.

A couple of other ad networks you may want to test are:

http://www.azoogleads.com - for affiliate/lead gen opportunities http://chitika.com - product based advertising

What kind of startup are you thinking about?

Microsoft AdCenter (Bing & Yahoo!) works about as well as Google for me, there's just less volume available. Facebook works as well, but they won't even show my ads unless I bid around $0.60/click or higher... I didn't expect that. Affiliates are the best ROI by far.

I've had some success buying display ads on specific sites through BuySellAds, just beware that all their biggest publishers are web design blogs that, for whatever reason, never convert sales for any product I've tried, even directly related to that profession. I guess the people that read "25 fresh green web designs" articles every morning have no disposable income.

* MSN Adcenter - Lower CPA * Facebook Ads - Longer term engagement (not necessarily lower CPA, though) * Affiliates - You give them a CPA and they figure out how to get you users :)