Well, I'm not saying that FS2004 is past it's use-by date, but FSX has seen a steady growth over the last few months. So it's time to 'rationalise' the price structure for older FS2004 products.
Auckland City for FS2004 - download NZ$12.00
Real NZ Wanaka & Tekapo FS2004 -- download NZ$12.00
Real NZ Marlborough for FS2004 -- download only NZ$15.00
Real NZ Wellington Intl and City FS2004 -- download only NZ$15.00
These are new RRPs, rather than 'specials'. Auckland and Wanaka/Tekapo have new boxed prices, but for boxed versions of the others you'd need to purchase the FSX version where it includes the FS2004 version, or the FS2004 Collection.
Note that the FSX prices remain the same, and I don't have any plans to change them for quite a while.