Can you buy an item (that brings you joy) during the year of aveilus – if it’s on sale and you don’t think will be available for that price after the aveillus ($600 vs. $1,000)
It is permitted to buy furniture and utensils during the year of aveilus, as the prohibition only applies to wearing new clothing. Even clothing are permitted to buy if you will not be able to get them later at this special low price. The new clothing however should not be worn during the aveilus, unless they are worn beforehand by someone else.
Pnei Boruch 18-12, Livushei Mordechai O:CH 3-184 brought in Nitei Gavriel (Aveilus-2) 10-32, 13-5. Regarding buying new clothing, in the case at hand not buying the clothing would be considered a davar ha’aved, which would be permitted, similar to buying new clothing during the nine days, that is permitted for a davar ha’aved. See Kovetz Halachos Bein Hamitzarim 12-1, Poskim.