The brake line is a tube called "Bundy" tubing specially manufactured for automotive brake line application, which can see pressures up to 3000 psi. It's not expensive and widely available in any auto supply house.
If you can't get the exact length of tubing, you should consider investing in a tube cutter and tube flaring kit to make your custom lengths. It should cost around $30. Bending the tube can be trick...if you don't do it right you can kink the tube and render it useless. They sell tube bending tools (not expensive), but if you're resourceful you can do a decent job without these tools.
95 E320 Cabriolet, 131K