is it mutar sell one’s personal for seforim for any or all of the following reasons:
1) to buy different seforim
2) just for the $
Answer:
If one has old sefarim that one doesn’t use, it is permitted to sell them.
One should preferably use the money for buying new books, but this is not a full obligation.
Best wishes.
Sources:
The Rosh (Menachos, Sefer Torah 1) writes that today the mitzvah of writing a sefer Torah applies to books – Chumashim, Mishnayos, Gemaros, and their commentaries – so that he should learn them with his children. He adds that a person must not sell the books, unless he needs the money to learn Torah or to marry a wife.
This halachah is ruled by the Shulchan Aruch (Yoreh De’ah 270:2).
However, the Beis Yosef (Choshen Mishpat 248) writes that the common custom is to sell books (sefarim), and we are not stringent concerning them as we are for a sefer Torah.
The Magen Avraham (153:23) suggests that the prohibition against selling sefarim might only apply to shul sefarim, and not to a private collection.
The Peri Megadim further suggests (E.A. 154:24) that it might be permitted to sell sefarim for the purpose of buying other sefarim, and this is written as a certain ruling by the Aruch Ha-Shulchan (Yoreh De’ah 283:6).
Thus, based on the common custom it is permitted to sell the sefarim, and the money should preferably be used for buying other sefarim.