I have some really nice Black Neons and Albino Black Neons in stock.
I'd be tempted to go with Cardinal Tetras over Neons, since they're bigger (less likely to get eaten, but still a risk) and like warmer temperatures more than Neons. They're essentially the same colors as Neon, with a longer red stripe.
Glad to hear the neons are working out well. They are not usually available from most club members. I'm not sure, but I don't think our vendor/sponsors usually carry them, so you'll probably have to go to a LFS or a chain.
Tropical Lagoon in Silver Spring had some a few weeks ago, and I think that store usually has them.