Dark Sphere Games (a UK distributor) has posted that Games Workshop will be upping the price on 242 items effective the first of June. It looks like the prices on these items is going up by an average of 12% - that's a pretty steep increase.
I embedded a google spreadsheet below that shows a list of all the models that will be changing price. The original items only had the price of the items in pounds so I added some extra columns where I converted the price over to US Dollars. The prices on those might not be 100% but they should be pretty close.
Looks like it might be a good idea to stock up before the end of the month!