Where would I buy the items for the Big 3? I have checked my car today and noticed a few wires going into the one big positive and negative and wondering if there is someone that makes 0 or 4 gauge wired for both or some kind of kit I could buy off ebay maybe? Make it simple for a moron like myself

Nice premade bolt on wiring would be real nice
I'm from Canada BC so would Lordco or Napa or any of the stores have anything like this? or would I have to go to a audio store if I don't have a clue how to do it.