These look pretty cheap! - £4.69

http://www.screwfix.com/app/sfd/cat/pro.jsp?id=91763

no doubt they wear out faster than the discs !

I've got 3 of them. See my previous posts re. this.
I'd rather have 3 @ a fiver each than one Makita or Bosch for a days wages.

here here i got one for cutting,grinding and one eith a sanding/flap disc on it beats changing over all the time, and to be fair although cheap they have gear box lock as well.