Whether you're looking for a cheap, expensive or free campaign management software, the list of ad servers below may help you out. Here, we're comparing the costs of ad serving between 2 million and 1000 million ad requests per month. Over the last years, ad serving costs have been greatly reduced. Price rates were collected in March 2018 directly via the vendor's website.
Moreover, with the latest advances in artificial intelligence and machine learning, modern ad serving technology can estimate the CTR for a given visitor in real-time. This increases your revenue in case you're paid on a CPC basis.
Some third-party ad server companies, like AdButler, charge for CDN hosting: those additional fees are not included here. Especially if you're serving video ads, charges may increase rapidly.
Similarly, some vendors may charge you for applying a white label to your ad serving domain (i.e. ad serving from your own domain by adding a CNAME DNS entry).
We can therefore state that the number of impressions is always lower or equal to the number of ad requests.
Keep this in mind, especially if you're making lots of ad requests for native ads or VAST tags. The VAST tag is called from the ad server, but an impression is counted only when the video starts playing.
In New York, price rates for a 4-week rental of a large physical billboard like the one above are at a stunning $14,000. During that period, your advertisement may be seen as much as 32 million times. To put that in perspective: that's about $437 for 10 million impressions, or an eCPM of $0,04375. Major disadvantages here are the inability to accurately count how many times your ad was seen, and not being able to target the ad to a selected audience.