The set of 17 bushings for the 58 is made by a company called rare parts. They build suspension parts for old cars and fabricated the set for the 58 with some help. As my memory serves me they are in Calif.
Pricey yes but remember they put a lot of time into getting them correct so the intall goes well.
I agree that for 17 pieces of rubber it's high but one could go thru the same procees and I would bet you have more than 800 in the fabrication if you include some of the labor.
Sun Prairie, Wi