Hi Alan, can't help with the monopod as I use a Manfrotto 790B monopod (£29) but it wouldn't be suitable for using as a trekking pole. When hiking I hand hold, although am considering a Leki for my longer treks.
As for the ball head though, the Giotto MH1302-652 gets a good write up in this months ProTog. 400g, load 8kg, list price £70 (but they are always excessive so expect you can find one for £50. If I was after a ball head then I would be going for this one.