Why do you want to 'build' a show car? You could just walk down the street yelling "look at me"
If you really want to do it then you'd be spending your 8 or 9 grand on the paint alone, then you'll need a bodykit (I guess) and it would want to be something that is of decent quality and that will not date too quickly... you dont want to cover it in a couple of grands worth of paint only to junk it a year later.
Wheels, at least two grand most likely more
Exhaust can be mega expensive or cheap... since you're not planning on driving it cheap would do.
If you're going to do it, then I'd think you'll be looking at 12 o 14 grand before you get to the obligatory 'phat' retrim, stupidly loud stereo, and engine mods that are just there for wank value.
woftam if you ask me, but its your cash. Just remember it will cost more than you think.
And if it doesnt people will think you suck because your car isnt as fully sick as the one next to it because he has two more tvs than you
Personally, I'd copy the old JMS R33 but do it in a deep blue, and DRIVE it (not cruise in it, drive in it) because it had presence and I don't think that Jap trends will die too quickly (look at all the oldskool race replica cars in Japan, they still look good, but anything that was in Hot4's more than two years ago looks pretty damn ghey)