Just to put the story straight, this is part of the official New Zealand WW100 commemorations. The New Zealand Government and the Wellington City Council, along with commercial sponsors, have engaged Peter Jackson to lead the development of the Great War Exhibition (as I understand it, Jackson and Weta Workshop are also majorly contributing themselves).
This diorama is just a part of the whole exhibition, for which the Perrys were engaged to sculpt the figures.
Initially the plan was to get the figures painted commercially, but Rhys Jones, a keen wargamer (and also, as it happens, the former Chief of the New Zealand Defence Force), suggested the idea that NZ wargamers could be offered the chance to do their own commemoration event in this Anzac project by painting the figures.
This is totally in keeping with the thousands of other Kiwi volunteers who are doing all sorts of projects and events to commemorate Gallipoli, such as embroiderers, artists, actors, schools, writers … the list is endless. In other words, the effort, skill and materials each wargamer, embroiderer, artist, writer, actor etc puts in is their own commemoration – it isn't a paid job.
A similar community project is the "call to yarn" campaign to crochet 18,000 woollen poppies for the Army Museum, where those involved provide time, skill and materials.
Anyway, I don't think the savings in painting costs would make up for the huge organisational effort to enable 100+ painters to get involved. Just think of the transport costs alone to distribute penny packets of figures all over the country, and to get them back in (all paid for, by the way).
The plan is that this diorama will be housed in a museum after the four years of the Great War Exhibition are over, and that it'll be an enduring commemoration legacy.
More info on the official project FAQ here: link