Are you kidding Wombat?
The price you pay for something is rarely linked to what it's worth to you!
That kind of black and white statement avoids the point entirely. My willingness to pay £1.30 for a litre of diesel in no way represents what I think that litre is worth. I have no choice but to pay whatever they charge.
The price you pay is always what it's worth to you, otherwise you won't pay it.
You do have a choice about paying £1.30 for diesel. You can choose not to buy diesel. The fact that you continue to buy it means that it's worth it to you, and that you prefer it to the alternative, which is not driving so much.
Example: If the price of diesel was such that it cost you twice as much to drive to work as you could earn in a day then you could give up work and be better off. In this case the price would be higher than what it was worth to you, which you would prove by refusing to buy.