Hi! Just a guess...
If you want to offer eggs to be hatched 'as a fertility / hatchability test', "Chicken Hatching Eggs - For Sale" would be the place.
You *could* list them as BIN with $0.00 as the price and whatever shipping will be (or as an auction and see where that goes).
If you want to find eggs to test, "Wanted To Buy" would be the likely place to post.