amp wires
 

Amp wirring kits are pretty expensive.
I was thinking of buy each part separately.
1/0-gauge cables from a local hardware store for power and ground
RCA and speaker cable from some audio store
and the fuses and connectors from either hardware or audio store.

if i do this, ill save half of my costs.
But is there any reason why not too?
are the 1/0-gauge cables any different from the ones you get when u buy a pre-made kit?

If you can save money and still maintain quality, then I say go for it. The only reason not to is if you happen to find a kit for super cheap.

some of the cables in hardware store have different ranges for 1/0 gauge, although the insulation may make it a 0awg sometimes the actual copper stranding is far less and more considered to be 4awg. Make sure you buy proper wiring, if you're running 0awg then you are probably doing some serious audio equipment. Car Audio products for Amplifier wiring such as Power and RCA's are designed with withstand extreme temperatures from the winters to the summers, as well as rca's with twisting and twining, it offers better shielding so that alternator whine and other such that don't exist in homes, are controlled.

wheres the best place to buy connectors, ring terminals ect..
not in packages of 10+ like bestbuy and futureshop sell.
does any shop sell them per piece.?

Most independent shops will be able to help you out with all of that stuff. The box stores maintain their 50-80% profit margin on that stuff. You may be surprised at how inexpensive it is to shop at an indy store for all of your car audio needs. Revscene has sponsors in this category. Check them out first.