Quite often, furnished apartments are privately owned. If they are, then each one will be unique and prices will vary quite a bit depending on the type of furnishings, size of unit and location.
In vacation areas like ski resorts and beachfront areas, expect to pay a hefty premium.
Obviously furnished apartments are ideal for of stays up to several months or even years. They are not practical and may not be economical for very short stays. For stays that are less than 1 month consider other options.
There is, of course, a strong correlation between price and quality. Pay attention to rentals with respect to features, amenities and services. In high rent areas or resort communities, expect to pay a hefty premium for luxury furnished apartments.