Just came across some computer grade DC-DC converters at http://www.synqor.com/synqor/synqor.nsf/Content/852566E9:007BF8F7?OpenDocument They are all 48 volt (36-75v) input so far, they have a 12V-12.5Amp and a 15V-10Amp unit (150 watt), both $130 in single unit quantities. Size is 2.3x2.4x0.4 inches.
