these 'step up converters seem quite pricey.. one that might fit the bill I spotted at Element14: ~AUD $120.
http://au.element14.com/mascot/8862-12-12v/converter-dc-dc-40-5w-12-12v/dp/1183943
MASCOT 8862 12/12V DC/DC Converter, Switch Mode, Fixed, 1 Output, 10 V, 16 V, 81 W, 13.2 V
Mavic car...