Which retired items are you talking about? If you are talking about the recent Morostide ones, we picked items that are going out via Carl or Pete (for old ToT/old morostide restockable) and I unretired some older normal items for the last round of Morostide achievements. :) I do take those things into consideration!

SBQ achievements are all added while the set is still active! And you can still get those items once they retire from the Gifts of Fashion Past. As for the Universal Trainer, the Universal Remote gets added to the Crystal Shop from time to time. I don’t know about the situation relaxing, people panic and buy the items for achievements causing inflation but you might find some people in the Achievements forums willing to lend out their set if you don’t get lucky from quests. :)