I bought my SV fully faired, so can't really comment on how good it is at wind deflection cuz I don't know any different
But I commuted 50 miles a day on mine and loved every second of it =]
All I have on mine is Fender extender for the front mud guard - good for keeping most of the crud off the engine - excellent if you're commuting
£30-ish i think
Tail tiday which I just bought from and had installed by GS in Ballymena £60
Tank pad/sticker £20 to help prevent scratches from your zips and stuff
My next investment is prolly gonna be Xenon style bulbs for seeing better/further in the dark (now it's coming in to winter) and a new exhaust... I'm still running the stock can, but I've drilled the baffle out of it so it sounds pretty throaty now, but not just as evil as a proper aftermarket can
My SV also came with a touring style (quite tall) double bubble screen on it, so I haven't changed that =]