A forum member wanted to swap seats - offering a low one for a standard one for the pricely sum of zero pence. Might be worth a look:
http://www.ukmonster.co.uk/monster/s...ad.php?t=16834
Also look for a company called Bum Wraps who can cut down you seat and while their at it, cover it in some snazzy like a different coloured vinyl or perhaps something ironic like leopard print. As well as the height, I would take some off the width or 'girth' as it is known in some quarters. Once you are moving you can slide back into the wider comfy part of the seat and the narrow part at the front is perfick for traffic lights. Seem to remember it was about £50-£60.
If alcantara (a faux suede) tickles you fancy, a fellow called Glyn on the DSC (Ducati Sporting Club) does a cracking job - for about £30 if I remember correctly - as long as you are happy with grey or black. The material itself is about £80 a metre
One last thing to think about is to find a second hand one and do tghe cutting yourself and then just get it covered. At least then you'll know it's the right height. Try to avoid lowering the suspension if you can as it'll not ride as well.
Hope this helps
simon