I don't know about price. But there are definitely differences between flosses. Waxed vs unwaxed. Waxed are better at cleaning. flosses vs floss. Flosses are extra plastic that are half to the environment. There are coconut and silk floss that are compostable. Probably best choice and I have only seen waxed versions. Better for your teeth AND better for the environment.
Flow is a personal choice. Gum conditioning can affect the decision. If one has deep pockets then they may want a floss that is more threadlike thicker to fill the pocket… a more specialized floss and therefore more expensive. If one has fairly healthy gums a bargain no frills floss may be fine. Price is not always indicative of quality. I have more than one rooted out a bargain in my lifetime a real steal!