Gemara in Baba Kama (p.9) discusses the value of "Hidur Misva"-to perform Misvot in a beautiful fashion, and not just fulfill the minimal requirement. The Sefer Hasidim (Rabbenu Yehuda HaHasid of Germany, d. 1217, Siman129) elaborates on this principle, based on the Pasuk, "Kabed et Hashem MeHonecha-Honor Hashem with your wealth." He says that just like one buys a beautiful jewelry box to hold his valuables, so too one should buy a beautiful case for his Tefilin and holy books. This is the source for buying a nice Tefilin and Tallit bag. If one stores his physical possessions nicely, how much more so he should keep his spiritual ones.
On the other hand, in Siman 878 he writes that one should not delay performing a Misva until he is able to do so in a beautiful way. For example, he shouldn’t pass up the opportunity to buy a simple Etrog or Sefer Torah, because he is holding out for a special one. As soon as he is able to do the Misva, he should immediately seize the opportunity.
The Mishna Berura (Rav Yisrael Meir Kagan of Radin, 1839-1933, Siman 656:6) discusses the Gemara that says that one should spend up to one-third more for the beautiful Misva. If one spends more, that is "G-d’s part." He cites Rashi that explains that if one spends even more than the required one third, he will receive the reward not only in the next world, but also in this world. The Mishna Berura also brings an opinion that someone who is very wealthy should spend even more than one-third.
SUMMARY
It is better to seize the opportunity to perform a Misva in a simple manner than delay until it can be performed beautifully.
