Thanks heaps for the great replies everyone.
I ended up getting a:
- AliExpress rotating 1/2 inch CIP/spray ball for $19 (has the slots for cleaning the sides and a hole at the top for shooting a jet directly upwards)
- Submersible pump: 60W 3000L/h (so they say) for $38
That flow rate with that size ball should be enough to make it spin pretty well. I should have enough fittings already to make it all work. From those with the BB or the keg king iteration, is the cleaning of the posts/spear via the quick connects a worthwhile functionality I should add?
Thanks for the advice thus far.