Kevin is going to be your best bet. A couple of other guys keep breeding stock of a few species and will have posts on IG and FB every so often. Chris Craig comes to mind and I’m a fan of his.
You can find some random odds and ends through Wetspot, Dan’s fish, aquabid, imperial tropicals, and a gentlemen out here in SoCal that keeps a breeding facility in his garage. He has Festae, Parachromis Multifasciatus, Andinoacara Stalsbergi, Carpintis, and other show stoppers but thing particularly rare.
I do miss COTA, and have done business with them many times. Unfortunately with them ****ting down their retail business, it makes it hard to get species like some of the rarer Vieja, Chuco, Astatheros, Darienheros, and rarer strains of common fish like the Usamacinta Salvini.