I have never tried to purchase livestock from Ebay before (I didn’t even thought it was possible)!
But I’ve began to see more and more offers available. The most important thing is to find a reputable seller, make sure the reviews and feedbacks checkout.
Here is a gorgeous Betta fish for sale by Aquaworld68, with 91% positive rating. In my opinion, that is really good. If you sell enough livestock, you will end up with some negative feedbacks no matter how good your livestock and service is- most of it is the delivery’s fault, too much air temp shift, too much agitation, too long of a delay, etc can all result in the livestock being distressed and die. And when that happens, it’s entirely up to the grace of the seller to save their own reputation by righting the wrong caused by the delivery services.