Twitter's fees are set dynamically, but the variability built in to the rate is confusing and disarming. My first click cost $1.30, but I'm not sure why, and Twitter doesn't do a good job of explaining how rates are set. However, Twitter did suggest that my ad might generate between 62 and 104 clicks per day. (I skipped the option to pay more to promote my Twitter account directly.)
My ads began showing up within minutes. There doesn't appear to be any manual approval process. Reporting is simple and straightforward.
Ultimately, Twitter did not perform as well as promised. After four days, the ad received just 67 clicks, under a quarter of the 248 minimum clicks promised for a four-day run. The ad was promoted 7529 times, which works out to a great clickthrough rate of .89 percent. That's double the rate I got with Google AdWords, and at a CPC of 94 cents, it was the least expensive investment of the bunch on a per-click basis, too. (I also got two new followers on Twitter along the way.)
The verdict: The total expense of $62.87 is pricey for such a small number of impressions, but the clickthrough rate is still impressive.
StumbleUpon: Cost-effective without clickthrough
At StumbleUpon you don't bid for impressions. Instead, you pay a flat rate to have your ad displayed to "stumblers" as they use the website. You don't write ad copy and you don't even have to rely on an ad being clicked upon. The page you're advertising just appears in the Stumble flow of users as they click along. Ad impressions cost a flat 10 cents each, an amazing bargain.
I paid $100 up front and set a $25 daily limit for my ad to be displayed to users with an interest in business topics, then submitted my Null Media home page for review. StumbleUpon's evaluation took about six hours, at which point my ad began displaying. (Make sure you submit each page you're advertising to the regular StumbleUpon system as well, because the ad reporting tool tracks both paid and organic Stumbles.)
Because no bidding system or variability is involved, StumbleUpon's tracking is very straightforward. Over four days, my ad was displayed 1001 times (or 250 times a day at 10 cents each), and my website received a surprisingly high 397 organic stumbles on top of that. While I paid $0.10 per paid ad view, the "effective" cost per view including the organic stumbles was just $0.072 per view.
The verdict: These are very cheap ads, but there's no way to track engagement of those viewers. The effectiveness of advertising a B2B service on a heavily consumer-focused service is also questionable.
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