Despite the proliferation of sliders, motorised ones are still quite expensive. Without motors, they’ve dropped to ridiculously low prices. But it’s really not that difficult or expensive to convert a standard manual slider into a motorised one.
This video from Max Maker demonstrates how to turn a very inexpensive slider into a more practical and useful one. It takes a little machining and a few parts, but it’s fairly straightforward. It just takes a little planning and a few tools.