Blue Zoo and LiveAquaria are a mixed bag when it comes to this kind of fish. You might get lucky but more likely you will end up with a loss. At least that is my experience with them. And when it comes to sexing, only Blue Zoo offers it and doesn't get it always right.
Ideally, you try to get them through a local store where you can pick them yourself. But even that doesn't guarantee that you won't have losses. I for example just this Saturday found a baby Janssi pipefish at my preferred store. Despite having tigger pods as live food and eating a little it was dead today, only 3 days later. If these fish don't get treated right on the way to us we are pretty much helpless.