John,
I see!
If your buying 'used' then (below) is probably your best forum option. Shipping from over here (USA) would be prohibitive for anything over a few ounces. Buying new, obviously Jaymic & Linwar (maybe others in UK as I've been gone a loooong time). Walloth & Nesch have shipping discounts now & then, so, worth a try.
Oh, and if your feeling bullet proof, there's always FaceBook.
Good luck with the tii.
BMWs from the Neue Klasse era - Index page
WWW.02FORUM.CO.UK