Can someone please explain to me why before Y"T the local kosher supermarket was charging $10 (bli guzma) for a honeydew melon, but I was able to buy one in a regular supermarket for $2.88? Now, let me be fair and say that the honeydew in the regular supermarket was smaller, but still, I could buy 3 of them for less than the price of that one melon in the kosher market. Is this fair business practice? (And don't even get me started on the price of esrogim.)
In 242 sk"2 M"B writes that if fish sellers drive up the prices, the Rabbis should make a takanah not to buy any fish until the market returns back to the normal level.
Why do we celebrate Sukkos in Tishrei and not in Nissan? The well known GR"A explains that when BN"Y sinned with the cheit ha'eigel, the ananei ha'kavod went away. On Y"K Hashem said salachti ki'devarecha, on 11 Tishrei Moshe announced that they would build a Mishkan, for 2 days they collected donations (ba'boker ba'boker = 2 days), on the 14th the money was turned over to the artisans, and on 15 Tishrei construction commenced. It was then that the ananei ha'kavod returned; therefore, on 15 Tishrei we sit in sukkah as a zecher to ananei ha'kavod.
R' Mordechai Ezrachi asks: if the ananei ha'kavod went away because of the sin of cheit ha'eigel, why did they not return immediately on Y"K when Hashem said "salachti" and forgave that sin? Why was the return triggered only by the start of work on the Mishkan?
He answers by quoting Rabeinu Yonah in Shaarei Teshuvah (1:42) that it's possible for Hashem to forgive a person for their wrongdoing and absolve them from punishment, but still want nothing to do with that person. Therefore, the sinner needs not only teshuvah, but needs tefilah as well, to ask Hashem to accept their avodah and restore their relationship to what it was before.
Y"K may have taken away the threat of punishment for cheit ha'eigel, but it did not bring BN"Y back to the same closeness to Hashem that had existed beforehand. It was the enthusiasm for BN"Y to want to build a Mishkan, the desire for "Shachanti b'tocham," which repaired and restored that relationship, and only then did the ananim return.
This is why, he explains, although a person can fulfill the mitzvah of lulav in seconds -- "m'd'agb'hei nafik bei," just lifting up the 4 minin is enough -- we spend hours before Y"T trying to select the best lulav, the most m'hudar esrog, etc.
In the midbar, it was the preparation and collection of materials for the Mishkan that showed BN"Ys love for Hashem and their desire to return to the relationship of old. Today, it is through our preparations for the chag, our extra hidur in its mitzvos, that we try to do the same.