I have been using SIP scooter shop in Germany for the last year or so for all sorts of parts for Vespa and an Aerox I owned.The site lists every thing in English and prices everything in $AUD.I just had a look and they are charging $373 for the LV pipe and $66 freight using Fedex.
I actually bought the stainless Scorpion pipe for my GTS250 and am really happy with it and that was around $330 + freight.Good throaty sound under acceleration but very civilised when on a steady speed.I was worried it would be too loud for the neighbours because I leave for work before 6am,but no problems.
I've had four or five packages from them and around a week for delivery is about average.
Also, I think that when you do the exhaust you should change to a slightly easier breathing air filter.I got the Malossi red sponge for about $11.
It just replaces the standard foam one in the original airbox.I'm still to chicken to go to a full pod filter and the Malossi sponge keeps everything looking stock.
PS: the SIP website is so easy to use and to find things that I always end up buying way more than I intend to.Don't say I didn't warn you