Keep an eye on Aldi , they do Bluetooth headsets for about £29.99, last time they had then in the were selling them off at 19.99. They will allow you to talk to each other, listen to music, and or Sat Nag.
There are some cheap Chinese ones on the bay as well.
Helmet type doesnt make too much of a difference, my pal has a hornet and the mike is glued to the chin piece rather than a boom mike.
Steve