I just bought a 5 metre length of welding cable which was like $5 a metre, a battery box which was $20, a roll of decent electrical tape $5, a cable joiner $3, a positve battery terminal $3 and a pre made Earth cable $12. Slammed battery in box in the spare wheel well, ran cable under car along the brake lines and attached ground to a bolt hole on the body and chucked the positive cable on.
Battery is a big sucker i got for $100 bucks as a cashie.
Works mint.
Thought it was pretty good value