Now, I was in Tesco during the week, and noticed a Thing about the Bran Flakes.
Here are the 750g packs of Bran Flakes:
And here are the 500g packs of Bran Flakes:
I apologise for the less than awesome quality of the photos, but you can't be too conspicuous when you're hanging round taking photos in Tesco.
The thing to note is this:
750g pack = 98p
500g pack = £1.84
So 750g = 0.13p per gram
while 500g = 0.37p per gram, which is almost 3 times as much.
Note: Other brands of Bran Flakes are available, although they may be called something else, such as 'Breakfast Flakes'