As I am aware, locations of outfitting items change quite often. There is no noticeable pattern to their change though. It has been noted that they are verified to change after an update, and after several days a station's inventory can change as well. Of course certain stations are more likely to carry certain items, so some changes may not even be noticeable. Tracking a specific item is difficult, so unless someone has seen it within a day, it probably won't help you.
Given this, one location you might want to try is Beta Sculptoris or LTT 377. These are two locations I know to have nearly every outfitting component consistently. Likewise, Beta Sculptoris has 15 of the current 20 ships in the game, although with the new discounts from powerplay, I would advise purchasing from a discounted station instead. Good luck.
