Right I know this is going to be a wild goose chase for some but for those in the Birmingham area (Spring Hill Tesco) it might be worthwhile.
I saw a Tesco post for a 1TB for £15 on here and thought I'd check my Tesco. Obviously they didn't have it. I saw a 3TB hard drive marked as £71.14 and though well I need a hard drive and that is an okay price compared to Amazon / Ebuyer etc. I went to the till and it scanned as £50 (The Mac Version). I instantly asked the guy behind the counter for another. They brought down the wrong one (Normal Version) and that scanned as £53. I didn't want to push my luck so bought them and ran.
Anticipating some cold here as I know it won't help most but hopefully helps some of you in the Brum area.
Edit: Went in today and they have marked them reduced to clear with the prices I got them at. There was also 2TB ones at £48.