I think the "photo-real" stuff is split over a few [different] sources - some freeware some payware/donationware.
Your first port of call would have to be Rob's stuff (
www.windowlight.co.nz). I always want to push this, as Rob's very active here and I'd rather we endorsed his products ourselves than have him accused of using NZFF unfairly to "promote" his sceneries. Anyway - there seem to be a few options there if you want to buy the whole lot (!!).
Mike's Hamilton is another obvious one that springs to mind. It's a beaut!
Then we're about to suffer an Aussie invasion (ORBX). They've already stolen our racehorse, our Pavlova etc. ... now they want to nick our scenery

.
As far as "is it worth it"? I'd say most definitely YES - but you may not need to buy *the whole lot* to enjoy NZ just a bit more. That said,I know of one person that hasn't got *any* add-on scenery at all - preferring to have decent framerates throughout ... and still loves it.
It's always toss-up between spending limited money on *aircraft* (or other utils) as opposed the environment in which they operate. Horses for courses.
EDIT: Ooops! Just re-read your post. Do you mean specifically/exclusively *photoreal* as opposed to regular scenery with photoreal some tiles?