The limit on spending for a mitzvah

Hi,

Normally, we say that there is a limit on what one must spend in order to fulfill a mitzvah; one need not spend more than 1/4 of one's assets [חומש מלגיו]. However, this is only where spending mitzvah is only a means of enabling the mitzvah, such as in purchasing an etrog. Where the spending actually is the mitzvah, such as in pidyon haben, one is required to spend whatever percentage is necessary.

(Rav Moshe Feinstein, Igrot Moshe Orach Chaim 5:41)

Have a great day,
Mordechai