How many eggs are you looking to sell? Just to your friends and family? More than that?
How many chickens do you want? 25 is pretty standard, but some, like at McMurray Hatchery you can get a Rainbow layer assortment. 25 chicken that lay different colored eggs. I ordered the Brown Egg Layer Assort. last year and then sold half of them. Turned out the wrong half because now I really like barred rock and i sold most of mine. That is neither here nor there.
I get a LOT of eggs from 11 hens. More than I need. I am taking some to work and I am trading them with my sister. She gives me bread she makes and I give her eggs. The number of eggs will taper off in a few years though.
Check out the Sell section of this board and you will find some people selling things. Where are you in IL? I am in WI and on the boarder.