have you considered having thermo electric coolers? like peltiers? seems cheap enough. http://www.ebay.com.au/sch/i.html?_trksid=p5197.m570.l1313&_nkw=peltier&_sacat=0&_from=R40 and from here it seems that they can do bulk pricing for over 10 pieces of motors. hopefully it helps. http://www.pc-cooling.de/Motors/DC ...3046404/1.13.046.404 - 24 V DC Motor.html#top looking forward to it mate.