We are in NY for 3 weeks and my wife would like to buy a new sheitel, the only way the sheitel will be ready in time before we leave is if she goes for a fitting during the 9 days. is it permissible?
In principle, such a purchase, which is a major purchase that brings a person joy, should be avoided in the Nine Days.
However, if this is your only opportunity, and if you don’t buy it you won’t be able to buy it elsewhere, it is permitted to buy it.
This does not, however, mean that it is permitted for the sheitel-macher to prepare the sheitel (if she is Jewish), and to avoid this problem you should go to a non-Jewish sheitel-macher.
Sources: Mishnah Berurah 551:11; 49. Concerning preparing new clothes, see Shulchan Aruch 551:7 and Mishnah Berurah 46. The same concern will apply to the preparation of a new sheitel.