I have no idea if these are any good, I haven't used them and don't plan to buy one.
However, they look ok and the price seems good. I have purchased other items from Pyramid and they delivered quickly and the parts were of good quality.
Anyhow, here are the links (and the coupon code for 40% off)
http://www.pyramidparts.com.au/products/interphone-bluetooth-500-intercom (http://www.pyramidparts.com.au/products/interphone-bluetooth-500-intercom)
http://www.pyramidparts.com.au/products/interphone-bluetooth-1000-intercom (http://www.pyramidparts.com.au/products/interphone-bluetooth-1000-intercom)
Arnie