There's a company called 'Ognibene' who are making rubber cushioned sprockets (front and back if you need them) in 15/16/17t at reasonable money - I've been using them for the past 4 years and they do make a difference (the front ones anyway) - you can find them on fleabay quite easily - and the GXSR600/750 ones fit as well.
I tried a front and back cushioned combo this time but did not notice any drop in chain/sprocket noise...buuuut the gearbox has done over 80k and is getting a little whiney, so it's difficult to differentiate.
+another 1 for the D.I.D chains though - best ones I've used by some margin but they're not cheap, however, as I see it they're like tyres and brake pads - all critical bits of kit, so get the best you can afford, then you can stop worrying about it.
