Like most things in life you only get what you pay for quality does not come cheap, the same unit from Aliexpress costs around $80aud(free shipping) against approx $160 including freight if you buy from Highpoint (who don't ship to Australia anyhow)
It really does depend on what you are wanting to do with it. If you want to do astrophotography with automated focus they are not really very useful as you need repeatable positioning for that, but if you just want to focus without shaking your scope, as bojan is suggesting they would be a good thing as you can focus while hands off the scope.
I have actually got one that I would sell cheap (It is minus the flex coupling, which should not be hard to get and needs to match your focuser anyway and I just put a battery in it to check that it functions) it has just been sitting on my shelf for a couple of years, it came with a box of other stuff that I bought. I would sell it for more or less postage and petrol money to post it, better that someone who will use it has it.
I have all my ED80 solar scopes set up with the SW/ Orion motor, belt driven to the 10:1 focuser knob.
This gives a fine, shake free semi remote (I use a longer RJ9 cable) focusing from the office.
Works very well for me.
I got one for my Saxon refractor. It is FAR better than manual focusing as there is way less shake and I like it enough it'll stay on for planetary stuff, but I'll save the shekels for a quality one for the new rig.