you'd be better off making one, that way you can have one to suit your personal needs. just take your time and plan it out. work out how many outputs you'll use, (chargers, discharger, fan, etc.). its probably a good idea to add a couple more, and a 20 or 30amp fuse, just in case. there's every chance you will find at least a couple of home made units at any race meeting sitting on someones table. you can ask them on building advice, im sure they will be glad to help you out. if you want more help i can PM you photos of a couple i have made.