Adjustable height desks do not necessarily mean 'sit-to-stand' desks, however in recent years there has been a lot more data supporting the health benefits of 'sit-to-stand' desks and are increasing in availability and popularity. As a result of this popularity prices are dropping.
Crank adjustments are usually the cheapest, then pneumatic and electric motors being the most expensive. However new technologies in production recently are making electric motor adjustability a lot more affordable. See below at a selection of desks and the price.
Some companies make custom designed desks that are tailored to the working area and space available. Costs savings can also be made where the desktop surface, if removed, can be placed on a new frame that will adjust in height.