I know that eggs should be bought before Pesach. However, we do not have space in our fridge to store all the eggs needed from before Pesach. What is the source for this minhag / halacha? And bedieved can I use additional eggs purchased during Chol Hamoed?
Some have the custom to buy foodstuffs before Pesach.
The reason for this is that should there be any chametz in the foodstuff, it will be nullified before the festival (since the foodstuff was already prepared before the festival). This will not be true if the chametz was not nullified before Pesach.
However, this custom is only practiced by few, and it is certainly permitted to buy eggs on Pesach if it is hard for you to buy them before.