I finished the appendices this week, and the book weighs in at a meaty 102,000 words. To put that in perspective, the previous two books were about 95,000 words each (with II Crimsonstreak being slightly longer than I, Crimsonstreak in total length).
In its current, unedited form, III Crimsonstreak's main story is about 85,000 words (similar to II Crimsonstreak, which was about 84,500 words but considerably longer than the original book, which was a much briefer 72,000 words).
As for the appendices, the third book is about 17,000 words. That's more extra material than II Crimsonstreak (11,000 words) and less extra material than I, Crimsonstreak (a whopping 23,000 words). The extra length of the third book's appendices is due to a long-form magazine article and a pair of short stories.
And, just because I like to fiddle with Photoshop, here's a completely unofficial mockup of a promotional banner:
