I went to buy mezuzos for the new apartment we are renting as the halacha says that one may not take down mezuzos from his old apartment to put them in his new apartment. They were quite costly and given the fact that we are moving out to the boondocks our apartment is quite large [and inexpensive] and that requires many mezuzos. I could have bought less than the most mehudar but this talk where he told the story of the man who had a fancy car with the best leather plush seats bought his son cheap leather tefillin and he remarked how shameful it was kept playing over in my mind, so I forked the big bucks over. It helped that I was with my son and I wanted to teach him that for a mitzva we go all out.
I have to work on myself to STOP CARING how much mitzva items cost. A mitzva is priceless so whatever I am paying is a bargain.
Not to care about money is an avoda.