This fella basically relies on creating false information relating to what irtems currently in game are going to be needed for the expansion and then selling them to "investors"
ideally, you want to create a website with lots of information and links to the expansion news etc available on the net and a section on confirmed crafting requirements for jewlecrafting or the other professions post expansion.
You try and drive "investors" to that site.
Obviously you make it all up - prefably after putting in place a purchasing program to snaffle up all the peacebllom, mossagate or whatever it is you are saying is going to be needed in the expansion and then putting it back in the AH immediately at a healthy markup.
Why wait till the expansion to make a profit selling cheap materials - do it now.
Perhaps we can brainstorm amoungst us some pausible scenrios - becasue investors like doing their reseach and for this scam to work it will need to be reasonably well organised.
TThere is no reason why you wouldnt do this accross a number of servers to buy up inexpensive materials and try to generate a pool of cash on those servers.