Hi Harry, I have a Viper helmet, flip front and Bluetooth, works really well for me and quite cheap if you think £150 is cheap of course, on my second one now, wife bought me a new one at Christmas, other one is sitting in the cupboard upstairs. If you want my old one your more than welcome, nothing wrong with it no scratches and never been dropped, had it for 2 years but only wore it in the summer (yeah I know !!) In silver and has 2 very small holes drilled into the outer cover NOT the helmet to mount my camera. Oh yeah the size XL or 62cm if that helps, got a big head (urk!) been told that before not funny anymore ok? Otherwise I would suggest that you go try one, I find it really fits well.
This one RSV131 I think, my new one is the RSV151.RSV151