Seller perk423 on ebay has done a few sets of brake pipes for me. Under £60 for a full car set in cupro-nickel with brass unions. Half that if you want (but why?) copper with steel unions.
Always good comms and willing to discuss a special job. Quick postage. All pipes labelled and tidily packaged. Not been disappointed. Currently he's on 100% / 18,000 feedback.
Unusually, to successfully find his classic Mini sets in cupro-nickel, omit the word "classic" from the search - try instead: mini brake pipe set cupro
Tip: if you're using any of the MiniSpare's rear subframe regulator valves (single-circuit cars) remind him to do double-flares on the valve end of the cross-subframe pipes: the valves have a 'volcano' inside the female outlets even though they take male fittings - unlike all other females on the car including the female *inlet* on the valve. I'm sure he'd do double-flares at no extra cost on everything - I read that many prefer them even on male fittings.
Contact and sales via ebay seems to be preferred by him. But he also posts his email which is [email protected]