Sometimes, market forces work in your favor. When AFTRA, the union that includes most voice-over announcers, forced stations to pay extra to use their talent on streaming audio, it pretty much eliminated the benefits of streaming for commercial radio. Non-comms haven't had the same problems. In fact, stations with a mission to serve as wide an audience as possible have become some of the world's most-listened-to online streams.
If you're really ready for radio promotion, college and non-comm stations are still your best bet. Their reach is getting wider every week. Just remember that you've got to provide them with music that works on their station and can sustain getting played 90-100 times per station before you start to see any significant results.