Just wanted to share the setup i put together when I found out the Sena gear cost $150.
Bluetooth Audio receiver $6
Any of the ones on Ebay like the one above works.
Helmet Speakers $5
Aerostitch also sells these if you want a reliable source. Most likely the same product though.
1. Roughly sew the speakers into the ear area of your helmet. You don't have to be a tailor about it, it just keeps them in place and flat when you put the helmet on. If you are worried about washing your liner, make a separate stitch to cut so you can work out the little speaker.
2. Stuff the excess wire behind the liner. Some tape will help it stay in place. Being handy with a soldering iron, I spliced it shorter.
3. Using a spare adhesive strip from a 3M Command hook you have laying around, stick the bluetooth module to the helmet. I put it near the bottom of the back, hoping to keep rain off it.
4. Plug the speakers into the module and pair it with your phone. Enjoy music and GPS directions piped into your ears.
Side Note: I use
OsmAnd for Android for GPS. The custom route function is great for scenic routes and by making the GPS directions go through the notification audio, you can set its volume seperate from any music you are playing.