There is no such thing as one price for ketchup.
Looking at how much shoppers paid for a 36-ounce bottle of Heinz ketchup (in 2007), we can see $1.66 was the average. However, among 279 transactions, prices ranged from $.50 to $2.99:
When I parked in a NYC garage, my experience was rather similar.
What My Parking Coupon Cost Me
Yesterday, I paid $34 for three hours at a Manhattan parking garage. The person who followed me paid $61 for two hours because he had no coupon.
We could say that it cost me less. But not necessarily.
To get my $27 discount, I had to…
- Remember to use my Icon Parking app before driving into the city. (Icon is a parking garage owner in NYC.)
- Find the link to the garage I had selected among their hundreds of locations.
- Open the link to reserve a spot.
- Enter my payment information (that at first did not work) and email.
- Open and scan (which also malfunctioned) my email when I picked up the car.
While the hassle was well worth saving the $27, it represented what the savings cost me.
Shopping Behavior
Not all households hunt for bargains. How often you shop, the number of stores you visit, and whether you use coupons each determines how much you save. But they also reflect the opportunity cost of your time. Perhaps for that reason, households with more employed people pay higher prices than those with fewer working adults. Recent research also indicates that age matters.
You can see older households pay significantly less than the young: 
Our Bottom Line: The Cost of Time
Paying less typically requires more time.
A recent paper cites three possible reasons for the variation in Heinz ketchup prices. There could have been different prices at different stores. Or, in the same store, Heinz ketchup might have been temporarily on sale, or cheaper because of a coupon.
For price deviation, ketchup is typical:
Except for those who were lucky enough to shop regularly in a store that had a sale when they needed ketchup (or some other item), time related to the lower price. An economist might have cited the tradeoff between the marginal cost of a dollar and the marginal cost of time.
So yes, for my ketchup and my NYC parking reservations, I save either money or time.
My sources and more: An NBER summary report and this paper had the price details. Though somewhat dry reading, the topic is fascinating. In addition, one of my favorite go-to blogs had a discussion of the topic.
At econlife, we last looked at parking coupons during 2017. The market changed since then because now, in many lots, you are required to pre-purchase your spot rather than just reserving it.
