I never complained about any overweight part time hybrid commuters, at least not ones in Seattle.
But seriously - a lot depends on how often you ride in dark conditions. I use a $20 front/back planet bike set, that takes AA. If they start to go dead half way to work it's not that big of a deal. I don't depend on my lights to see my way, just to be seen.
So I'm thinking you should get a fairly decent bike mount light that takes batteries, just to see how it goes. If you find you really need more light then you will be able to make a more informed choice before you drop some major $$$'s.