FM Broadcasting for Spatial Audio

Our group has been discussing using a spatial audio setup during the beginning of the performance. One way of doing this that we have discussed is to broadcast audio using FM radio to a number of boomboxes located around the pond. We could simply buy an FM transmitter like this one: https://www.amazon.com/0-5-Fail-Safe-Long-Range-Transmitter/dp/B003FO4UHW/ref=sr_1_1?ie=UTF8&qid=1336750605&sr=8-1. This transmitter would broadcast over 100 yards, which seems like a good distance. But, we could also build our own transmitter, which would be a lot cheaper and more fun. This looks like a good set of plans to build one: http://makezine.com/projects/super-simple-fm-transmitter/.  This specific design would only broadcast over 30 feet, but we could boost the range by adding an antenna.