"Data" is becoming an indispensable production factor, just like land, infrastructure, labor or capital. As part of this, a myriad of applications in different sectors require huge amounts of information to feed models and algorithms responsible for critical roles in production chains and business processes. Tasks ranging from automating certain functions to facilitating decision-making in data-driven organizations increasingly benefit from acquiring data inputs from third parties. Responding to this demand, new entities and novel business models have appeared with the aim of matching such data requirements with the right providers and facilitating the exchange of information. In this paper, we present the results and conclusions of a comprehensive survey on the state of the art of entities trading data on the internet, as well as novel data marketplace designs from the research community.