I would take care if buying direct from China on ebay. As I have stated before, what appears the same horns as those sold by reputable importers are often made by other factories to lower standards, so the quality of those on ebay can be questionable. The worst I have ever heard was of euphonium which arrived with no holes through pistons!
If it sounds too cheap to be true, be doubly beware
Bloke, at the risk of being out of line, have you talked to either Matt at Dillon Music or Vince at Tuba Exchange, who both do exactly that for their store brands?