Or, the high savings of good planning.
If there's a trip you could do by mass transit, but you leave late, so you have to drive and pay for parking, or take a cab, you've just cost yourself money.
If you go out to eat, or get take-out on the way home, because you don't have groceries in the house, you've just cost yourself money.
In almost any case where you have to buy something in an emergency, because you didn't plan ahead (and have the chance to go someplace you know it's cheaper), you've just cost yourself money. All the more so if it's something you already have and now you have two of them.
Overall, you can save not only a lot of money, but time if you don't live your life in a way that you have need of so much convenience. You can cook a healthy meal from scratch more quickly than you can go out to a restaurant and get served. But that requires groceries in the kitchen. When you account for the time spent on grocery shopping, there may not be much time savings, but not much time loss, either, and you're eating more healthful food for much less money.
If you plan an appliance purchase ahead, you can research what models are best, what good prices are, learn whether there are predictable patterns for when they'll be on sale at a discount. If you wait until the day you absolutely need it, then you're pretty much stuck with whatever Best Buy has on the shelf.
This is such a general pattern, that fatigue is the only limit on how many examples I could give.
Where are you paying extra for convenience? Is it really even all that convenient?