That is the only recommendation I can make too - all the small commercial ones I've ever seen look disappointing...
Mill with your lathe, quite an interesting experience.
I do, hence 'lack of effective' my set-up somewhat lacks rigidity
I have made two types of ball turning attachments for my minilathes, see:
http://mikesworkshop.weebly.com/ball-turner.html
and
http://mikesworkshop.weebly.com/ball-turner-mk-2.html
Mike