The McFarlane Stranger Things figures appear to be landing in a number of stores at clearance prices recently including Bargainmax, Zavvi and reductions in Game.
You can now add B&M to that list, with the Series 3 figures (white card) of Hopper and Eleven now on B&M shelves at just £9.99 each. This is 50% off the RRP, but I suspect finding mint cards might be difficult as these are being forced into a shelf too small for them and it is bending many of the cards.
You can also find the 11 inch deluxe Demogorgon figure. This wasn't priced or on system in the store I went in to - and others have reported the same. I am reliably told this is priced at just £14.99