Sometimes it means, "there isn't enough money to pay for that." Certainly, among the undeserved poor, this happens all the time. And for things like health care and education, tragically, it happens too often.
But most of the time (in the commercialized, wealthier part of the world that many of us live in), the things that are within the realm of possibility could be paid for (even the edge cases could, if we found friends and neighbors and went deep into debt). One person might say a stereo or a sizable charitable donation or a golf club membership is "too expensive" while someone else with the same income might happily pay for it. "It's too expensive," almost never means, "there isn't enough money if I think it's worth it."
Social entrepreneurs are often chagrined to discover that low-income communities around the world that said their innovation was, "too expensive" figured out how to find the money to buy a cell phone instead. Even at the bottom of the pyramid, many people find a way to pay for the things they value.
The same is true for real estate, ad buys and productivity improvements in the b2b sector. If an investment is going to pay for itself, "it's too expensive," rarely means, "we can't afford it."
Often, it actually means, "it's not worth it." This is a totally different analysis, of course. Lots of things aren't worth it, at least to you, right now. I think it's safe to assume that when you hear a potential customer say, "it's too expensive," what you're really hearing is something quite specific. A $400 bottle of water is too expensive to just about everyone, even to people with more than $500 in the bank. They have the cash, but they sure don't want to spend it, not on something they think is worth less than it costs.
Not everyone will value your offering the same, so if you wait for no one to say, "it's too expensive" before you go to market, you will never go to market. The challenge isn't in pleasing everyone, it's in finding the few who see the value (and thus the bargain) in what's on offer.
Culturally, we create boundaries for what something is worth. A pomegranate juice on the streets of Istanbul costs a dollar, and it's delicious. The same juice in New York would be seen as a bargain for five times as much money. Clearly, we're not discussing the ability to pay nor are we considering the absolute value of a glass of juice. No, it's about our expectation of what people like us pay for something like that.
Start with a tribe or community that in fact does value what you do. And then do an ever better job of explaining and storytelling, increasing the perceived value instead of lowering the price. (Even better, actually increase the value delivered). When you don't need everyone to buy what you sell, "it's too expensive" from some is actually a useful reminder that you've priced this appropriately for the rest of your audience.
Over time, as influencers within a tribe embrace the higher value (and higher price) then the culture starts to change. When people like us start to pay more for something like that, it becomes natural (and even urgent) for us to pay for it too.