I believe the problem has nothing to do with the speed at which things sell or the difficulty of implementing a search filter.
I believe there IS a search filter in play right now that is reducing the list of available items so that the ones I need are not available to me.
Before I built the Vu Tower I saw a LOT of Vu Tower items. Again and again. As soon as the Vu Tower started being constructed, I saw maybe half as many. As soon as the Vu Tower was finished and ready for use, I saw almost no Vu items.
When I need Table, I see almost no Table, and when it finally shows up and I visit that City to get it, it is either not shown or when I tap on it it is magically not available. Later, when I don't need Table anymore, Table is available to see and to obtain.
I can get items I don't need. I can't get items I need. It's that simple and I believe it's done on purpose to try and get me to PURCHASE those items.
EA has to make money. I would buy the game or pay a subscription fee. But I will NOT pay to avoid playing. Buying my next advancement is not "playing" the game. It is paying someone else to play the game for me.
This Global HQ problem makes me want to quit. Congratulations, EA, you've broken a great game.