I am looking for a new pair of tefillin (for myself). Can I use maaser money for part of it? For the difference between “kosher lechatchila” and “mehudar”?
If yes, I already made out with a sofer to get for X amount, without thinking I was using maaser. Can I now add on with maaser money to that to get a better pair? Can I pay any of the original X amount using maaser. (Our budget is very tight as is, before adding in the cost of tefillin.)
According to many poskim, the same way we cannot use maaser money for the actual tefillin, since it is our own personal obligation, and we cannot use our own money for it, the same would apply to the hidurim of the tefillin, because it is for our own benefit. Therefore you shouldn’t use maaser money for your own tefillin. A person that gives a chomesh, may use the extra tenth for a hidur mitzvah.
As a side point, if you are tight and you don’t have enough money for your own needs, you might not have to give maaser at all.
B’orach Tzedakah 11-5.