My solution to not buying a bike GPS / intercom system was that I purchased a relatively cheap car GPS which had a headphone jack.
Unfortunately, having ear plugs into my ears hurt after several miles - and it was very noisy.
I then purchased a Bluetooth Helmet only to discover the Bluetooth in my GPS would not emit the correct type of signal to communicate with a headset (different codes - too technical for me)!
So I then purchased a Bluetooth Sony gadget which plugs into the GPS headphone jack & converts it into a Bluetooth headset signal & it worked! But it is still noisy over 60mph.
Conclusion - save up and buy the proper stuff LOL
However, someone has just pointed me to Rocket Radio which has a headphone jack to plug into a GPS or similar system & rather than ear pieces has velcro flat headphones, all for £20 - so that may be my next trial as I'm still reluctant to buy a bike GPS... lol
Striving to live the ordinary life in a non ordinary way