Here in Shiloh a number of neighbors bring in supplies of lulav, etrog etc to sell. I'm so used to the fact that the "arba minim" are as easy to buy as milk and eggs. I was going to write "challah" as one of the things that are easy to find in stores, but I really want people who aren't in Israel to understand that in most Jewish neighborhoods in Israel these "specialty items" are standard fare. I know there are some wonderful Jewish communities abroad in which challah is not something you can buy from a store. You have to bake it yourself.
Israel is a very small country, so if these holiday items aren't in a local shopping area, generally you don't have to travel more than twenty minutes or less to find some. My husband used to enjoy going to the big arba minim markets in Jerusalem to get in the mood and pick up his four species, but now he buys from some neighbors, the same neighbors every year. Other neighbors bring in the large palm branches to be used as s'chach to cover the sukkah. A few days before Succot they drop off the amount ordered in front of each house.
Baruch Hashem, this is a Jewish country. It's felt most of all during the Jewish Holidays.