I’ve bought a LOT of eBay eggs. Something about the lure of late night online egg shopping gets me everytime.
I’ve had good hatches and terrible hatches. My best advice is keep it within 500 miles of your location. For me, in the West, that’s about 1 state away. That’s made the biggest difference in hatch rates. All the cool stuff always seems to be on the opposite end of the country but I’ve wasted enough money on eBay eggs to have some mild restraint.
Ask the seller as many questions as you need to: additional pictures, shipping procedures, guarantees, NPIP.
I consider it a gamble. Just like any shipped eggs. Which is some of the fun for me. It’s also given me some decent contacts. If I want eggs from them again I reach out directly to the breeders (bypass eBay).