Hi Dave. I wired my car last year and went through all of the options. Here's what worked for me.
I got most all of my wiring supplies from Graeme at Larpro (larpro.com.au) in Sydney. He supplies in bulk lots but will break them up if you ask nicely. Prices aren't listed but he's dirt cheap and provides good service. He's supplied a few Cobra builders in the past.
I used 0 (zero) gauge battery/starter cable which is 13mm diameter and has lots of fine strands, which is apparently what you want.
BAT0BS - Battery & Starter Cable 30 Meter
I borrowed a hydraulic crimper to press the lugs on. You don't want them coming undone and touching the chassis rails. The crimpers are pretty affordable now:
NEW-8-TONNE-HYDRAULIC-CRIMPER-TOOL-SET-4-70-mm
Grab plenty of heat shrink from Larpro, he's 1/4 the price of Jaycar. Get red and black in different sizes and remember the size you order will roughly halve in diameter once you've applied the heat gun.
I bought an $80 Bosch heat gun from Bunnings (digital readout so you know when its up to temp), a self adjusting wire stripper (
like this) from Jaycar and also a ratchet crimper with removable dies - so you have one tool for insulated and non-insulated terminals of different sizes, about $70 from memory.
I soldered all wires properly instead of using those joint blocks. If you haven't soldered before the page below is a great help.
How To Make Perfect Solder Joints
It's handy to have good electrical connectors near all lights and accessories. I bought about 20x each of the 2, 4 and 6 way connectors, see below (you need male and female). Check that they come with the brass male/female terminals - mine did. Slide an inch of heat shrink down the wire before crimping, then slide back up over the end of the terminal and apply heat gun. That way you don't have any stray terminal ends accidentally exposed.
LARRIKIN PRODUCTS - Category Electrical Connectors
I used plenty of good electrical tape at 30cm intervals to keep looms together and black conduit in various sizes to protect wiring from
oil, water, abrasions, etc. Cable tie the conduit to your chassis rails or you can use a hot glue gun to fix inside fibreglass panels.
No doubt there are better ways to do these things and you may already know most of that, but hopefully it helps someone. Good luck.
PS. Buy/borrow a good multimeter!