Egg prices from farms are going to vary greatly by the time of year. In the spring, they are super cheap because the hens are laying like crazy and everyone is overflowing with eggs. Around here, it's kind of like zucchini in the late summer or pears and sugar plums in the fall. It's not unusual for people to drive around offering eggs/zucchini/pears/plums to their neighbors for free!

By late summer, farm eggs are less plentiful and prices will more closely match what you'd see in the grocery store/farmers markets. In the winter, non-factory farm eggs are expensive.

Also, farmers markets are usually cheaper than stores, but more expensive than on-farm stores because they figure in transportation costs and what the demand will be. The cheapest option would be farms who just put up signs on the roadside as they have no overhead and are usually just trying to lighten their egg load at home (ask me how I know this! In the spring - $3 per 18 ct at my house! )