Ask yourself these questions. Would you be willing to invest less than $100 and a few hours of your time - I don't know how many, maybe 3, or 4 at most - if the return on that investment was a measurably better understanding of what your customers wanted from you? If you could come up with a few simple, but specific things to do that would raise the impression your customers have about you a couple of notches and make them want to buy more from you, wouldn't you do that? If you could easily find out what customers were really thinking, wouldn't you make the effort to do it?
Sometimes it's hard to know the "hot buttons" that customers have. They're usually patient, or at least polite. They walk away with their expectations having been met (kind of). They might come back and purchase from you again, if they don't have to go too far out of their way. But, perhaps you didn't knock the ball out of the park with that last interaction and are asking yourself how you can make it better next time, or at least have a little better feeling about what your customer was thinking.
Using online surveys can give you the answers you want to the questions above. You'll need to be willing to invest a little time and effort in the process, but it's inexpensive, there are several good sites out there that will make the process easy, both for you and your customers, and the dividends from doing it can be huge. You