The cost and time involved in installation depends on the type of lift or escalator that you install.
In general, escalators are fairly limited in terms of where they can be placed as they need a large amount of space underneath for machinery, oil and running gear, and the time and expense involved in installing them can be pretty high. You also cannot easily move or alter an escalator. A traditional lift suffers from the same set of issues.
However, a platform lift – the more modern alternative – has the advantage of installation anywhere in the building, and the modular structure means installation within a week and the ability to move the lift when required. As many platform lifts are also self contained, the structural disruption is minimal and you won’t need building works and scaffolding.