My favorite example of consumer surplus is my computer. I paid around $2,000 for my MacBook Pro, plus maybe $1,000 more for third-party hardware and software. But I would have paid much more—probably somewhere between the prices of my car and my house—if no substitutes were available. (It's hard to say that given what I know about how much computers "should" cost, but if I look at it rationally I can see the enormous value I derive from my computer.) The consumer surplus is off the charts.
As Austin writes,
Given the enjoyment and convenience obtained by the multitude of products we use it’s a wonder how little of that full value we actually pay. The rest is consumer surplus.
Given how I use my car and my computer, the computer should cost more. In a world with zero consumer surplus (where each supplier was a perfectly price-discriminating monopolist) my car would cost about what it did but my MacBook would cost, I would guess, around $250,000.
Thankfully we don't live in that world.