I have a few more questions.
Given the first volume covers only a small fraction of the whole publication, (AA-AL), I suppose there will be something like 50-ish volumes, and if each one is published every 2-3 month it could indeed take years (100/150 months = 8-12 years!).
What sort of guarantees can you provide to the buyers that the collection will surely be published so that he won't be left with half the volumes? Also, it may be difficult to keep the price steady for such a long period of time.
Have you considered a digital copy of the books? A protected pdf or something like that (I know there are some seriously encrypted formats)? That could speed up the release and perhaps lower the price as well?
I'm old fashioned so I love books, but I also came to appreciate the digital era. Also, 50 or so books, each about 300 pages, would take a lot of space
Now say I have $ 4.500 on hand (50 books at 25% off), could how long till I can buy the whole collection? Would I have to wait until the last release is out?
How much would it be for a digital-only copy?
I've been collecting some encyclopaedias over the years, and when I think of the overall price I sometimes wonder... but then I know it was worthy in almost all cases. Thing is they were all completed in at best 2-3 years, the most recent I did was over in a year with releases every two weeks.
The amount of work and material here is completely different but it's an awful lot of time and it may eventually result in people loosing interest and not completing the collection, a real shame.
I'm not trying to ruin your hopes in any way, I'm actually very happy that there are still people working hard on such projects without major publishing companies behind them (and often ruining the spirit of the project).