To be perfectly honest, I think you may be able to find what your loking for on ebay. I know its relatively unconventional, but one can find alot of good quality equipment on ebay.
IIRC, I have seen regulators for sale in the past. They were destined for industrial sized helium tanks, but the potential is there nevertheless. If you become really desperate, you can try international ebay auctions and hope for the best. Failing that, just find a local gas distributor and ring their customer service number.
If you feel confident, visit the premises and ask to speak to a technician. Good luck!