Bottled water - most companies claim it comes straight from the mountain or that it's more clean than tap water. Both statements are very often incorrect.
About 90% of the extra warranties cost when buying electronics are equal or more than the actual cost to repair the item.
You don't need to change your oil after 3000 miles. You can travel more than twice as long of a distance without changing the oil. Of course, why would the mechanic tell you that when they can get paid twice, right?
The price of french fries is 20x as much as it costs the restaurant to prepare them.
Why do textbooks cost a fortune? Because you need them, so the producer sets the price. Their price has little to none to do with how much it costs to print them.
Researchers discovered that sending and receiving a text message costs the carries one third of a cent. So what's up with so many of them charging so high per message sent?
Cinema popcorn sells at a staggering 1275% mark-up.
Your chance of winning in a typical lottery is around 1 in 14 million.
Premium gas won't clean your engine, or make it run better. It won't make a regular car go faster nor let it work better. But people prefer to pay for "premium" even though it doesn't give them anything more than a feeling of getting something better.
There are companies offering you to check your credit for free, then they turn out to be trying to sell you something first. Even though you are entitled to check your credit for free once per year, without asking any company to do it for you.