One that jumped out at me straight away was a product at my local supermarket that I found to be absurd. They sell packets of sliced apples in the fresh chilled produce section. The bags are little by anyone's standards weighing in at 80g. As you will see in the pictures below one packet costs $1.27 which in unit pricing equates to $15.88 per kg - Now that's expensive! One night I noticed no one had been buying them (perhaps the store got it wrong and people AREN'T suckers) and the product had been reduced to 64c which is still $8 per kg.
I walked perhaps 10 paces to the apple stand where fresh red apples were selling for $2.84 per kg. This means if you could find an apple that weighed say 200g it would cost 56.8c...but you would be burdened with having to cut it up yourself.
I understand the logic behind paying for convenience but this example just made me shake my head. Think about it, there's extra cost associated with the packaged product because there has been additional processing, the packaging, and the fact it needs to be in transported/stored under refrigeration.
The product (with reduced price)
The original pricing
The price for apples without the extra processing