My mum is obsessed with buying discounted and yellow label stuff when she sees it, which means she ends up hoarding loads of unnecessary stuff that will probably never get used up. Examples are:
Around 200 bars of various flavoured Lindt chocolate bars at 20p each. Original retail price would be worth over £400 if you assume each bar is £2 minimum! (The 100g bars)
10 bags of perfect ted matcha powder, usually retails at over £10 for just one 30g pack, she bought each bag for £1!
Both from bog standard supermarkets as well (sains and Tesco)