Well, I'm *pretty sure* that the white leghorns (or a mix thereof) are the chickens that are hatched out of the trader joe (and other fertile eggs found in supermarkets) eggs most of the time. So if people have those near them, they can get them for a few dollars. I don't unfortunately. Right this second there is a buy it now auction on ebay for white leghorns for 12 eggs for $7.50. The buy it nows usually run more than the auctions, since the people with auctions are hoping they'll get bid up high, and they usually start lower.
So, if I were going to sell white leghorn hatching eggs, I would probably ask for $6.50-9.00 a dozen. This is just my opinion though.
Another strategy is to place them up for sale high, and reduce the price until you have takers.