I too have thought the Stock Exchange could benefit from a "search for item" feature or more reliable "find and pay solution". I doubt we will ever see any change with it though. Why? Becuase it goes against the nature of "Freemium Apps". How so? If you REALLY want to update/upgrade your city EA is hoping that you will give up on patience and elect to spend some of your hard earned real money. They have already given you a quality game; albeit one that we wish had some better features.
Naturally we want to play at our own pace and we easily get annoyed when others hold back our progress; this is especially true when progress is limited by game developer design. It seems almost crafty. Because it is by design and therefore the nature of what "Freemium Apps" are, I doubt we will see any change to the existing Stock Exchange.
I don't say this to support EA's model. But it is the best answer I can come up with whether it be with this Freemium App or any other. EA if I am wrong then we all look forward to your reply.