I put a question mark in the title only because Alisdair may already have this on the list Cacti and succulents at:
www.uhlig-kakteen.shopSuppliers based in Germany and will post in Europe. I ordered a couple of things today and will let you know how the service went, I payed through Paypal but there are other options. Site very easy to use. English, Italian, French, Spanish and German language options.