i have been putting 91 benzene in it at 36 baht a litre but was wondering can it run safetly on any of the cheaper alternatives which would save around 60 baht on a tank full

If you referring to gasohol, yes, savings are substantial.

However, not all bikes can use this type of fuel.

Your bike should have a sticker on the tank indicating that you can use 91 gasohol (E10), I have done now 10,000 km on mine using 91 benzene, E91, 95 benzene and E95, it all works fine.

I prefer Shell E95 V-power or Caltex E95 Techron, more expensive but the higher octane gives better performance and the additives keep the engine clean.