I can't seem to find any on eBay.
It's a gray area that anyone sells them on there. Unless listed as livefood, animals are prohibited.
Millipedes, due to being toxic if ingested, don't make ideal livefood.

Most babies will be Captive Bred, but stay clear of Wild Caught adults.

£6 each seems a good price. Although I have just given away 30 for free.