I was looking at the website for Chainreactioncycles the other day in the hope of finding a threaded one inch headset (like rocking horse droppings and usually only cheap Taiwanese ones are available) and I saw '1" threaded Shimano Deore XT headset'. I ordered it for £19.99 thinking "Hmmm...". Hey presto it turned up next day and it IS a brand new Shimano XT one inch threaded headset. It is very modern looking, low stack height, sort of cartridge bearings and silver (unlike the original which was black and had quarter inch ball bearings).
Needless to say I am a very happy bunny indeed !