I see this thread is pretty much solved but other might find this useful so I'll chime in anyway.
I normally use AA or AAA powered lights and use a cheap versatile charger such as
this and use
high quality rechargeable batteries. These batteries will easily outlive the cheap ones integrated in the vast majority of bike lights and can be replaced in an emergency with readily available disposable batteries. For the lights themselves I normally use Cateye mostly
this and
this one, they perform well except for occasional susceptibility to horrific weather but they last a long enough for their low price and have good mounts which let them go almost anywhere.
It's funny, 'disposable' battery powered lights seem to be viewed as obsolete in a way now when in fact I find them to be far superior to anything in a similar price bracket.