I'm not a fan of Cateye front lights. That strap type bracket is pants.
You don't say what distance Audaxes you intend....or what time of year. I'm sceptical as to whether any 2 x AA powered light will be bright enough/last long enough for the sort of unlit country lanes favored by many audaxes.
I find a Hope 1 bright enough on even the blackest night - and lasts long enough for me to finish a 200km even in January.
£57.59 at
Evans - using their discount code NYDBATT - expires today. or
Wiggle have it at £63
Another 4 x AA which is highly rated in the Audax community is the B&M Ixon IQ. Much cheaper if you buy it direct from one of the German on line retailers such as Rose Versand or Bike 24. I've not tried that one.... but I might if Evans dont deliver on the Hope I've ordered for OH.