I'll second suggestions for Arc and Opalec add-in - both good choices, both can use lithium batteries.
Also, if you hurry, you can catch Arc's Christmas sale (ends this morning) - they have "taste of Arc" specials with a sample of their lights, plus discounts on purchases of 5 or more of any one light. I think the sale ends at about 10 or 11 a.m. - sorry I didn't see this thread earlier.
Arc sale page
Dave