We analyze the problem of minimizing the cost for satis- fying information demand in a network of moving nodes, where the communication between nodes is subject to dis- tance constraints and a costly communication link with an information source (central server or Internet). This prob- lem has applications in several fields ranging from vehicular networks to space exploration, and it is NP-hard. We pro- pose a novel indexing system that is able to reduce the search space and show that in practical cases, our system is able to find an optimal solution in a reasonable length of time. An extensive experimental analysis on large real and syn- thetic datasets shows that the proposed method responds in less than 10 seconds on datasets with millions of events and thousands of information requests, with an improvement of up to 100 times compared to the non-indexed solution.