Here in Anchorage I can have a tall custom Arch fabricated out of Aluminum for abut $750 and change, it looks just like the factory one. I’d check around your area and see who has experience in boat fabrication and also who has the best reputation.
The nice thing about having your own arch fabricated is you can add things like rod holders or kayak racks, etc, etc.
Last I check the factory Arch was about $1500 bucks + shipping.