Preserving source location privacy in wireless sensor networks can be critical for several practical applications. Existing solutions proposed specifically for sensor networks rely on a combination of dynamic routing and dummy traffic to hide real event messages. While some privacy protection guarantees can be given, these solutions also tend to be expensive due to fake transmissions and non-shortest path routing overheads. In this paper, we propose a novel idea, of using a combination of directional antennas, transmit power control and information compression to provide lightweight and energy-efficient source location privacy. We discuss the adversary model extensively and then carefully layout characteristics of a realistic adversary. We show how use of directional antennas makes eavesdropping more costly for a realistic adversary and establish relationships between probability of compromise of location privacy, characteristics of directional antennas and size of the adversary's eavesdropping network. Finally, we show how a simple information compression measure can greatly reduce message latency and prolong battery life by conserving energy. Results of extensive simulations in NS2, with our realistic directional antenna add-on, show that compared to existing solutions, we can achieve comparable privacy protection, better message latency, delivery ratio and many orders of magnitude improvement in energy consumption.