Volvo filters are made by Mann, not by Volvo. When you buy "genuine parts", Volvo put their stamps on the Mann filters & charge you extra for the privilege.
Have a look at the writing on the genuine oil filter closely for example & its highly likely you'll see both the Mann stamp & the Volvo one.
I'm servicing my S80 soon myself. I bought Mann parts from a local store, as they (Mann) manufacture the filters for Volvo after all. The oil filter was £8 & the air filter was £14. That's not a major difference to what you paid for those particular parts, but there's still a difference all the same for the identical thing without a Volvo badge on it.
