My business just got a letter from a (non-wargame related) vendor that they were drastically bumping up the price of their magnet-based products, and was having general problems getting some magnet-based products in stock.
Apparently Neodymium, the main metal used in rare-earth magnets which is primarily mined in China, had skyrocketed in price over the past year - from April 2010 to April 2011 it's more than tripled, and is climbing at a rate of nearly 10% a day. The pricing is not expected to go down any time in the new future.
(you can view the pricing history of Neodymium at here)
What this means for tabletop wargamers is that using magnets for quick weapon/head swaps just got a heck of a lot pricier, and will continue to go up for a while. Expect to see a shortage of rare earth magnets, coupled with some price gouging for the magnets available.
I'm not sure exactly how this will effect future PP models. PP tested the waters with their Bethayne-Belphegore box, (rather successfully, IMHO) but this recent increase in magnet pricing may put a this tech on hold for future models getting the same treatment.