You might consider doing the same thing that one of our WV re-enactors/cannoneers did when he built a carriage for his reproduction of a WBTS mountain howitzer: Use local talent. = A local welder in Gerretstown, who owns a small "job-shop", charged him a flat 30.oo per hour plus cost of the steel to hand-craft all the various pieces of metal for the carriage.
(MY "just plain guess" is that, if you look around your county, that you'll find at least one competent blacksmith/welder/mill-right/machinist/tradesman, who will happily "take the private commission" & do a creditable job.)
Btw, when our "Red Team" built our "half-scale Conestoga wagon" for the 2007 OK Statehood Centennial Wagon Train a "vocational arts" teacher from Broken Arrow (OK) High School charged us (I believe that I remember correctly) 600.oo (and he provided the "used materials") for handcrafting all the various metal parts of the chassis/body. - We provided the teacher a set of blueprints from The Smithsonian "historic vehicles" catalogue & he did the rest AND on time, too.
(Fwiw, "Jack" did such a GREAT JOB that our team invited Jack/LindaSue to "go along" with us. - They spent one day with us during the OSCWT, as both of them were then teaching at BAHS.)
yours, satx