Its not so much the breeder you have to worry about, its the couriers, they tend to be rough with the packages. Even though the packages are clearly marked "live animals/fish" they still get thrown about.
Watching a fish unboxing online and one of the bags had popped due to the courier not reading what was clearly written. This not a fish but 3 years back I bought a snake from a breeder and sent via TNT 24 hour courier. Got it the next morning, box was battered and huge hole in the box and could see some pressure was put on the box. The snake was freezing but thankfully alive.
So you can risk it but personally I'd rather either pick them up or go to a good fish store.