If you are hatching AND transporting them, that transportation can really kill hatch rate along with age of eggs. With small numbers, that 50/50 thing can be greatly bias due to small numbers. But, regardless, figure 50/50 hatch and 50/50 gender, with that possible 50/50 not making it. So if you just want one, which really you should raise more than one chick at a time, I'd get at least 8 eggs.
If you had your own birds and didn't need to transport eggs, had a bator that was well tested for where you are hatching and for the type of egg, (such as doing test runs with eggs that are less important, you could go with less of the type you want. But if you really want one, more is better to ensure the adventure wasn't a total bust.