A quick update on the kitchen: it's coming along well and is on schedule, though the mess is still indescribable. The messy, building phase should be finished at the end of this week, happily, though there's still a fair amount of work to do after that.
But back to silk velvet. So far, I have found three suppliers of pure silk velvet, across three continents.
Firstly, Oh So Elegant in Australia. I ordered a small amount of fabric from there for a test piece a while ago, and it was very nice indeed, though quite a light weight - more a dressmaking fabric than upholstery weight, but still good for smaller items. They were very nice to deal with, too, and sent my order promptly. Their velvet is currently Aus $100 a metre.
Next, Delectable Mountain Cloth in America. This firm was recommended by several people, but I have to admit to being a little disappointed. I contacted them to ask if they supplied silk velvet; they confirmed that they did, in an upholstery weight, but didn't keep it in stock and would need to order it in, at around US $200-$400 a yard (they weren't more specific). So far so good, but when I asked for further information - how wide is it? Can I order swatches? - I didn't get any response at all. I've chased a couple of times, but they're still to get back to me. Disappointing.
Finally, back to Europe, and Prelle in France. Prelle are manufacturers, not just suppliers, though they do sell directly too. They produce both silk and silk/wool blend velvets, in quite a heavy weight; the silk velvet is £274.60 per metre (I suspect that's converted from Euros), and the silk/wool is £280. They're very nice to deal with, extremely helpful, and supplied quite large swatches at no cost very quickly. There is a downside, however, in that their velvets are only 64 cm (25") in width, which may not be suitable for larger items, and means that it's even more expensive than it looks.
This is all the information I have so far, but if anyone knows of any other suppliers, I'd be very happy to add them to the list.