  The Web of Data (WoD) has experienced a phenomenal growth in the past. This
growth is mainly fueled by tireless volunteers, government subsidies, and open
data legislations. The majority of commercial data has not made the transition
to the WoD, yet. The problem is that it is not clear how publishers of
commercial data can monetize their data in this new setting. Advertisement,
which is one of the main financial engines of the World Wide Web, cannot be
applied to the Web of Data as such unwanted data can easily be filtered out,
automatically. This raises the question how the WoD can (i) maintain its grow
when subsidies disappear and (ii) give commercial data providers financial
incentives to share their wealth of data. In this paper, we propose a
marketplace for the WoD as a solution for this data monetization problem. Our
approach allows a customer to transparently buy data from a combination of
different providers. To that end, we introduce two different approaches for
deciding which data elements to buy and compare their performance. We also
introduce FedMark, a prototypical implementation of our marketplace that
represents a first step towards an economically viable WoD beyond subsidies.
