UPDATE: It's also available for £20 on the Xbox One at Cex.
Diablo III: Ultimate Evil Edition has held its value incredibly well since release, but this is the cheapest price I've sen for it yet. This is for a preowned copy, but with stores healthily spread around the country, you're easily covered if there are any issues.
I'm 70 hours in and yet to get bored with Diablo III on PS4. It's the co-op that's really pulled me in though, and I can't think of a game that I've played more in couch co-op since Street of Rage 2. With controls perfectly mapped to the controller, this was well worth the wait on consoles.
Thanks to PaulJennings.