Steel valve stems, local suppliers?

[Michael. 2312]

Looking for a BBS type steel valve stem as pictured bellow, would anyone have a spare or know a store where I could find such locally? 

I believe the ID of the wheel the suit is around 11.2mm standard size.

The top side washer / plate has an overall diameter of 16mm

[E30 325i Rag-Top 2914]

Would have though most large(ish) tyre and wheel shops would have these in? I don't know if there is a "standard" size for the valves or if these BBS one's require a different size, but most (if not all) of the new BMWs come with steel valves fitted and have had a few replaced by Carters off the shelf.

Different story if it's the valve with the tyre pressure monitor in it though - especially if you don't realise and just get it replaced, whoops! Computer says wtf??