As a customer: if I am on the fence about a product, I will rarely buy anything that does not offer some kind of money-back guarantee, even if the cost is only 10 dollars. I've been burned before by buying products or services that turned out to be trash, and offering a guarantee shows some level of faith in what your company offers. I've only requested a refund a small handful of times.

Most recently I bought a $550 dollar online course and the 1 year unconditional money-back guarantee was 100% the deciding factor for me to try it. I ended up loving it and will not be requesting a refund.