I am a little surprised that Ikea UK doesn't stock the item but I am sure that from the photos they could be available from a "pound shop" for about the same through not in the classical Black mine started as...now with a drip or 2 of brown.
I did a quick search and found this:-
https://www.ebay.co.uk/p/2256170059?iid=192531930252So you can find them if you are looking.
It is the one thing that has changed my paint finish with the adequate mixing of the paint. As some of my paint tins are very old but as they are sealed well and then mixed well they seem to last well. The other thing I do find with this mixer is if the solids have congealed at the bottom of the tin it will cut through the lump and mix it back into solution.
I have had to pull mine apart a couple of times as the switch became iffy and all I found was a standard small 3 volt motor which is the type made in the thousands to power battery toys etc. All it had was an over length shaft and a simple mechanical switch which can go out of alignment.. reassemble and away she goes again!
In fact over the last few years it is the best tool I have purchased/made in relation to modelling.
Off topic I use the coffee machine to make a nice coffee.... Latte, Cappuccino, flat white, any one? (it was a nice Christmas present from the family this year!)