Ohio's cold right now. Shipped eggs don't do very well below 40 degrees or so. If you do this, I'd do it next year.
There are plenty of people on BYC who will ship you hatching eggs--some at only the price of shipping. Try the
buy~sell~trade egg forum this spring.You have to have at least twenty posts to participate. They have all sorts of breeds, and I personally recommend Australorps or Easter Eggers. Australorps are nice, calm ladies, EEs are pretty and interesting. And they should lay green eggs.
But that's assuming you actually want to go this route.
You want to add two laying birds, right? So a 50% hatch rate is considered about average for shipped eggs. And then there's the male/female ratio to consider. Assuming you go exactly by law of averages, you'd want eight eggs--four not to hatch, two boys, two girls. Then you'd have to get rid of your roosters.
Just to point out how risky this can be; this summer, I had a hen hatch out eight eggs. Seven were boys. I also had another hen hatch out nine. Again, seven were boys. I also had a m:f 4:4 ratio, a 3:4 ratio, a 2:3 ratio and a 6:3 ratio. Currently, my little cochin girl (Sylvie) is brooding four chicks, three of which look to be cockerels.
I love hatching eggs. I think it's educational, and it's great being able to track development by candling. But it's also kind of risky if you're depending on it as a method of expanding a small flock.
Good luck with whatever you decide.