Can I buy a sheitel during the shiloshim for my Mother
Hamakom Yinachem Eschem b’toal aveilei tzion v’yerushalayim
Regarding your question, the minhag is that an avel doesn’t put on new clothing during the whole year of aveilus, and this would include a shaitel. However the actual buying of the shaitel would be permitted, if you are going to wear it when it is permitted.
Y:D 389-3, Divrei Sofrim Aveilus ibid 44, Kitzur Shulchan Aruch 211-10.