I agree with Microwire, I set up a dual battery System for $200 doing it myself, and the majority of that was $100 on a battery tray.
Suzies are easy to adapt one of the Supercheap 5buck trays..... You can get a Red Arc Solenoid for $75 off ebay.....
Get in contact with your local CFA. They change the Batteries in their trucks every 12 months so always have a surplus of 'old' batteries. This is what I did and they just gave me one, no charge.... They're a Century N70, so PERFECT for winching with... heaps of power.
And yeh, bout 20 or 30 bucks for the cabling.... Piece. of. piss
TF