If it's not a standard moulding, then a manufacturer will charge one-off setup costs to do a run, overall cost per metre will depend on how many metres you need.  If this is the way you go - don't under-order.
In Chch there are firms like Hardy and Thompson.  Not sure for the rest of NZ.  Presumably these days they'd use H3.1 treated pine.

I found a guy in the Wellington Region Wellington, "TImber Profilers Ltd".

He does not advertise, as he seems to be an "in the trade secret". I managed to find him through a local Joiner. He seems to be a one-man band in a workshop, making every possible timber molding you can think of for most of the major timber suppliers in the country.   

Yes, set-up cost, labor, and material all adds up.

Strictly speaking bolection mouldings are used to frame offset/non-coplanar panels so they have a rebate on the back though there are flat ones used to create the illusion of a panel where there is no offset. The term more relates to the function than the profile.