They have been showing up in LFS all over the Phoenix area. You might call around your area and ask. Otherwise there are always f0 flagfish on aquabid since they are florida native and people collect them to sell.
I received six f0 flagfish from Adrian a couple of weeks ago. I'm not sure how often he collects them or what his inventory is like, but the fish I received are gorgeous. Much prettier than the ones I bought in the LFS.
Well, although not livebearers they are endemic to the same biotopes as some of our beloved fish and they eat some algaes that other fish won't. I have kept them with both P. latipinna and P. velifera to control filamentous algaes with great success thereby leaving the clean areas open to other algaes those species love to graze on.