The best pace to get Touratech accessories from is www.Touratech.de but the only thing is you'll have to buy it from them there when you're in Germany as they won't sell 'direct' to the UK.
Last year I was lucky to be in the 'Schwarzwald' when the Touratech 2011 Travel Event was taking place and bought a few bits and pieces for my GSA30 and the stuff was a good bit cheaper than in the UK(20%)
Best thing was that they had a sale aswell up to 50% off some items......I bought a load of stuff and if you knew what you were looking for could save a small fortune...Had to brush up on my German quite a bit though and it was a bit of a 'Teutonic Scrum' in the sale room. I reckon the savings we made paid our ferry crossing........!
I've always had good service from the folks at Touratech UK though but still can't see why there is such a large price difference......!
To put it in perspective I've been in contact with a 'Chliean GSer' recently and he is having to pay nearly three times as much as we are in the UK for Touratech products
Second hand is a good option aswell and i've bought a good bit of stuff on here and saved around 40-60% off new price
Have a scan on eBay (UK), quite a lot of GS users take kit of bikes they are selling and advertise quality items there, just search Touratech BMW, I have brought quite a few extras for my GSA that way.
Sorry couldn't resist a little plug. Yep, all at Rugged Roads are fully paid up Tossers. Although I'm the only one on a GS at the moment
We design, test and manufacture all of our own products here in the UK. All of our products have been tested by ourselves or other Tossers and we do a good range of protection products for the 1200.
Take a peek and see what you think. If you've any questions we're always on the end of the phone/PM/email.