Back when first released, the Collector's Editions were £39.99 RRP and Manga's combo release of the movie was £24.99. That would make the difference £104.98. This is around what I spent (knock around £30 off for pre-release discounts), although I imported the AU movie disc before Manga announced it in the UK.
Right now, the complete BD budget collection is £39.99 and Manga's forthcoming movie standalone is £14.99, a difference of £55.98.
Naturally I'd much rather the former than the latter, but for the soundtracks, the artbook and the packaging, (no Blu-rays) there's no way I could justify £100.