I have a business selling eggs as well. I use all Barred Rocks, but also recommend sex-links. Make sure you get good quality birds, as they will pay for themselves by being good layers. Barred Rocks are very calm, great in cold weather, lay year round, lay nice big brown eggs, and the cockerels make nice roasters and the old hens good soup, as they are a large duel purpose breed. A Barred Rock pullet normally lays around 280 eggs in her first 12 months of laying. Also, make sure you give them 14 to 16 hours of light every day, and make sure that the lights come on before sunrise and turn off after sundown, as this will greatly increase their laying and keep them laying in the winter. It doesn't pay to keep the hens past 24 months, and sometimes they need to be replaced at 18 months to keep in peak production and be economical.
You can do pretty good selling eggs if you treat it like a business. I have sold ten dozen eggs today.
Let me know if you have any questions about start your eggs business.