I just went in Sainsbury's in Boscombe and found that they have reduced some of their kids Halloween costumes from £10-£8 to 50p! I couldn't believe my eyes when I saw it! It isn't all of their costumes but some. They had a Spider costume for the little ones and a few for boys and girls in the 11-12 age bracket. My store is a smaller store, so the bigger stores may have a better selection!
Reductions in other stores too ..