One of the themes of the holiday of Succot, is זה א-לי ואנוהו, “This is my G-d, and I will glorify Him.”
The lesson is that we are supposed to beautify all of the Mitzvot that we do, by not holding back the expense involved. We should try to purchase a beautiful set of Tefillin, nice Tzitzit, a Shofar that is majestic, and a Sefer Torah with perfect writing.
This theme is connected with Succot, because we need to go to the trouble of building a Succah, and purchases the Arba Minim, the four species. There is a wide range of prices and effort in these two areas. One can purchase a small, do it yourself Succah, with minimal decorations. Or, he can go to the trouble of building a large, beautiful Succah with creative and tasteful decorations. The Arba Minim can be bought for a small amount, or a much larger amount for the perfect Etrog.
Obviously, we should spend within our means, but the way we go about doing these Mitzvot, shows how much we cherish them, and how much we want to give glory to G-d.
It sends a bad message when we find the funds for trivial, unimportant things, but cannot bring ourselves to spend lavishly in the performance of Mitzvot.
The Halacha regarding Succah decorations, is very interesting. Once they are designated for the Succah, and are placed there, they may not be used for any other purpose. If they fall down by themselves, they still may not be used, unless a stipulation was made before the Chag.
Succot serves as the reminder to glorify Hashem by spending extra money, to show how dear the Mitzvot of the Torah, are to us.