Depends on quality...pet, breeder or show. I would sell my SQ black cochins for a minimum of $90-100 for a trio. Believe me, that's not expensive for folks who want SQ birds...whether they show or not.
Think about it. If you bought and had to ship a dozen eggs for...say...$40 (SQ, really good birds)...you would probably get about a 50% hatch. That means 6 chicks which may...or may not be the quality you are looking for. Also, you could get 1 pullet and 5 cockerels....so then you have to get MORE eggs to try and get at least one more pullet!
I think it's a better deal for me to just pay a bit more $$ upfront and have older, live birds the sex that you want.