It amazing that you started this journey a few years ago now.
I know you like the “unusual” goldfish ( to put it nicely, haha.
But have you ever considered doing butterfly koi? Yes they will outgrow your tank, but I think these might actually be profitable for you. You buy them T 2.5-3” at Hosi farms for 2 for $50, in the spring you sell them online for $50 each when they have double / tripled in size .
I did that last year in my and gave the koi to my uncle for his pond, but I could have easily sold them too.
Koi are hardier fish, have beautiful markings, have the long graceful fins in you go with butterfly, and if you want the metallic look, you could get the ginrin koi or ghost koi.