An 'Auto' fuse' is just one used in automotives, also known as blade fuses or car fuses. Dirt cheap on eBay.
100a is easy to find, and should be ample (pink in colour I believe), even at 100a and just over it'll take a few seconds before it blows.
If you put 2 fuses in parallel then you'll effectively double the amperage before they'll blow, but that's just more things to go wrong!

I solder and heat shrink my wires clean onto my fuses, one less point of weakness. If they blow it's a pain to change, but fusing appropriately should avoid that.