Sell 'em for as MUCH as you can get for them!
Here in West Palm Beach, FL I have slowly built up a small number of customers who buy my chicken's eggs. I deliver them to everyone once a week, because it's easier for me than to coordinate individual pickups. I charge $4 a dozen, delivered. It's just a small operation, no more than 10 dozen a week, and it just helps to pay for the chicken feed.
I've advertised on community bulletin boards, both actual and online. My best advertising comes from word of mouth. There are people who want farm-fresh eggs that come from hens known by name, not number, and are willing to pay that little bit extra.
Now I've been trying to find customers for my ducks' eggs. They really are a rare commodity, they aren't sold in any stores that I know of. I've gotten some calls from folks who do Google searches for duck eggs in West Palm Beach and find my posts. But so far no steady customers.
I'd like to find someone who does speciality or gourmet baking, or has a small restaurant, and wants duck eggs for their recipes. They can be used in egg dishes like chicken eggs, but I think they're best for baking. They have nice big golden yolks, and the whites are a bit denser & thicker. They give baked goods a nice loft. Even pancakes & waffles are better with duck eggs. My kids notice the difference, and after enjoying a pancake breakfast go out to say "thank you!" to the ducks.
I am offering the duck eggs in smaller quantities, 6 for $3, since most folks don't need many at one time. If I find more demand for them, I will raise the price then. I offer a few free to my chicken egg customers in hopes of getting them hooked on their goodness. Hopefully there will be more of a demand for them during the holidays when folks do more special baking.