How much does a DMP like Lotame or Exelate cost ? Assuming I'm a 10M unique visitor per month website editor, what would I pay?

Frequently publishers get paid revenue share of 50% when they provide data to DMP\DataExchange. Overall the cost of data for advertisers that buy it can be about 20% of CPM. Publishers would pay for DMP solutions only if they have some valuable data on customers that can drive lift in CTR and convertions that they can sell or for managing their own audience. In most cases the data from signle site is not valuable enough espesialy when site doesnot have data showing highly expressed "intent" such as search keywords or some search forms like air ticket or booking forms.

An important point to consider when pricing out DMPs is whether you are actually speaking with/considering a data management platform, or if you are referencing a data provider. The key component of DMP vs. DP is the 'management' piece. DMPs will typically charge monthly fees based on the unique number of users that will flow through the platform.Every DMP will have a different pricing model based on the inclusion of different features (such as the inclusion of augmented third party data, services offerings, advanced algorithmic modeling, etc).Data providers may offer data on a CPM basis per unique user, or a flat fee based on a particular campaign in question.

DMP vendors like Lotame and Exelate charge a monthly subscription fee of 5k-20k plus additional cost per thousand fees based on data usage.  You will also be required to sign a one year contract.