There's a lot of Veloce 10-speed hubs around but they do seem to attract a premium on eBay and it may make more sense to find older 10sp compatable Chorus/Record units which are obviously nicer. Alternatively and I've not tried this but you could research the possibility of changing a 8/9sp freehub for a 10sp, which will obviously give you more cheaper options.
Looking through eBay I can already see these...http://www.ebay.co.uk/itm/Campagnolo-FH ... 2a2e9b2093http://www.ebay.co.uk/itm/Campagnolo-FH ... 2a2e9b2093
It's sometimes worth looking through the current stock of larger online retailers as they often have recent NOS Campagnolo kit at reasonable prices e.g. Wiggle, ChainReaction etc