I have been looking for ammonium persulphate for etching, and all I can find is sodium persulphate(not very soluble) mixed with sodium bisulphate(acid, helps a bit) and sodium sulphate(dross). From the speed of etching and the quantity of copper etched, I think the bulk of the stuff is sodium sulphate. I can apparently obtain ammonium persulphate from the States in small quantities, at exorbitant prices plus astronomical shipping costs.
Australia offers fair sized tubs at reasonable prices but they can't ship abroad. A chap in Tyneside can offer me £1000 a tonne.
Does anyone know if I can get this substance in the UK at all, or is it one of those hazardous substances that little kiddies like us shouldn't play with?

 

Quick google search turned this up:

http://www.silverprint.co.uk/chem24.html

Seems reasonably priced.