Hi, I've been buying and selling eggs for a while now and here are a few tips. Whenever possible it is best to collect the eggs in person, this ensures that eggs are handled gently while in transit and you will usually get a much better hatching rate rather than using eggs sent through the post. It is always a good idea to have a look at the parent stock, then you can really see the quality of the birds and the conditions in which they are kept, unfortunately photographs don't always give an accurate portrayal of this. ( I am always wary of sellers who do not allow collection ).
When buying or selling eggs using the postal service it is best to have them packed in purpose built polystyrene boxes, I very rarely have had any broken , either sending or receiving. It is ideal to have the eggs wrapped in tissue to stop egg movement inside the box, (less chance of air sack damage) and stops any tiny pieces of polystyrene sticking to them due to static electricity caused by movement of the eggs, also it gives the eggs a little more air.
I live in N.Ireland, most of my eggs are sent to, or received from U.K. mainland and I find that Royal Mail 1st class if posted in the morning will usually arrive next day so maybe not worth wasteing your money on Next day guaranteed!
After receiving your eggs through the post it is best to unpack them as soon as possible. Then they should be placed in a similar way to that of your incubator. ie- if the eggs in your incubator are placed on their side then store them this way ( same for clocking hen ), or if they are placed upright in the incubator (pointy end down) then store them the same ( empty egg boxes are ideal for this ) . It is best to store them for 24hrs before incubation to allow them to settle but remember to turn them (or tilt the egg boxes 30 degrees) at least twice in this period. Then just follow your incubator instructions or place them under your hen.
Best of luck! Charlie.