So sad to see a skyline out of shape Feel for you man
In terms of prices, there are a few options
New Front Bar
Look for people wrecking an R33. You may get a stock front car for under $500 if your lucky. You could spend a bit more and get an eftermarket one, but that will be a bit over a grand.
New Re-Enforcment Bar
Once again, find off someone wrecking an R33. You should get this fairly cheap. One thing to look out for, if people have installed a front mount, this bar is sometimes cut, so find one that hasn't been cut.
New Radiator
You may as well get an alloy radiator. You can buy them from just jap for $400. Easy to fit too. There is someone in the group buys sections selling some china alloy ones for about $250-300 too.
New Air Conditioning Condencer
Not sure on this one, but look for some one with a wreck once again. Should be too bad.
Airbags Refitted
Have no idea on this one.
New Windscreen
These can be pretty expensive, but I'd call around to a few places. Not sure on figures tho, but could be up to $1k
New Bonnet
Just about impossible to find a stocko one. A wreck would be the only place, but most wrecks have damaged bonnets You can get an aftermarket one, but be careful to get one thats legal. Do some research on this.
New Headlights
These will be a few hundred. Try get off a wreck and bargain the price down.
When looking for these parts, be careful to get series 2 parts only for the bonnet, front bar and lights. If you get series one anything, the rest won't fit. Since you are replacing the whole lot, you could go for a series one face, by getting all of these as series one parts. They will all fit. So remeber... all series 2, or all series 1.
Hope this helps a bit