Two homes can pay quite different amounts. These are the things an installer looks at.
Straight or curved
The biggest factor. A curved rail is made to measure for your staircase, so it costs more and takes longer to arrive.
Length of the stairs
A longer flight needs a longer rail, which adds to the cost.
Indoor or outdoor
Outside steps, such as on a raised Queenslander, need an outdoor model built for sun and rain.
Seat and features
Powered swivel seats, folding rails, a higher weight limit and remote controls can add to the price.
Where you live
In regional and remote areas, ask how travel is priced and how quickly the installer can service the lift.
Warranty and servicing
Check what the warranty covers and what servicing costs after it ends, not just the purchase price.