The metric is not how much their prices have gone up. Recalling their film history, this tells us that their film used to be very cheap.
Originally Posted by 2F/2F
Compare prices today. Ilford is cheaper than Kodak for film (sorry, don't know paper off the top of my head).
5 years or so back, Ilford had really cheap prices. They were also supplying house brands (Arista, ultrafine, etc) who were selling at really low prices. Ilford had to reorganize.
There can be multiple reasons for the price increase. One just might be their interest in having a sustainable business.