It may be very helpful for breeding projects and rare item collectors to be able to set alerts for a trade search. Perhaps when searching for lions or items there could be a button that says "notify me of new trades" that would notify the player of trades matching their search. If spam is a worry, then the notification message could have an opt out, or the player could set a specific price range or number limit on the notifications they receive about it. It can be tough re-checking the trade center over and over, especially for a rare or hard to come by combos. I find my self struggling not to check the TC over and over for some admittedly specific parameters.

TLDR: It would be nice if players could set alerts for new trades matching their searches