I'm pretty sure we got our hens from Purely Poultry. Sexing rate was pretty decent. They claim 90% accuracy. We ordered 21 female chicks (3 each of 7 different breeds) and got 23. All of those survived to maturity, and only 2 were roosters.
We also got 9 chicks from the
feed store. My FIL wanted us to raise some Austrolorpes for him, so we got 5 of those and gave him 4 (we kept one just because he only wanted 4). Then we also got 4 blue laced wynadotts. One of those died in the brooder, and 2 of the remaining 3 were roosters. They were sold as sexed chicks, and the feed store wouldn't refund us for the dead or male chicks, which was annoying.