Reconditioned stairlifts may be an option worth considering. They are are usually straight stairlifts that have been removed from one location and can be installed in another. There are savings to be had and can be considerably cheaper than buying new.
Curved or made-to-measure stairlifts are not normally available second-hand because of the bespoke work required. Many suppliers will still provide a warranty for peace of mind.
Consider the age of the reconditioned stairlift. If you are looking for innovative designs and the latest safety features, they may not be available on older models but if the trade off is acceptable to you then it may save you money.