This is the response I got:
It is Games Workshop’s policy from time to time to review our entire range to ensure they are appropriately priced, which sometimes means certain items within our product range will incur a price increase. We feel the price of Citadel Finecast fairly reflects the increased quality of these models over there metal counterparts just take a look at this month’s White Dwarf or pop into your local Games Workshop store to see for yourself.
There you have it, folks... GW's answer to the Finecast range costing more to buy is basically "they are better"! I've asked them to clarify whether the production, packaging and distribution for Finecast figures costs significantly more than the metal versions... if the answer is equally bullshit (or they do not answer at all) I guess that'll be the end of me buying new GW products.