With all them mods you've listed, I reckon you could do it all cheaper if you can do stuff for yourself and look around for parts... $1500 is a lot for a stereo, i guess you can pay $600 for a set of front splits etc but a lot of people probably wont hear the difference... can definitely get a stereo that will cause hearing damage for that money lol.
Exhaust could be done cheaper, maybe just stick with a cat-back and pay less than $250 for an exhaust? My mate used a XR-6 T exhaust (twin 2.25" pipes) on his N/A falcon and paid $150 including a cat for the whole lot + $60 for a custom pipe to make his cat attach to his manifold.. and it sounded good too.. maybe a little quiet on idle but a good note when you got up it.
Get a remote from the wreckers.
Look around for parts to lower your car with, I reckon that could be done cheaper too. I know someone who bagged his falcon for less using new parts
Red leather wont suit in my opinion, unless you only meant you'd get them guys to do a custom job? They look pretty nice.