I had a quick search and I couldn't find this so I'm going to suggest it, let me know if it has been suggested/rejected before and I'll delete it though :)

I had a thought when I was looking through the trades I have made, I have some people watching them but the only real use of this is for the 'watcher' to easily find the trade again. What if we could send out messages to people who were watching that trade (limited to once per week maybe, and can only be about the trade). This way you can let people know updates, such as if you're willing to drop the price, so that you don't have to cancel and remake with the lower price, only for those watching it to not be able to find it again.

For example:
"There are 5 people currently watching this trade"
Message update:
"If anyone is still interested I am dropping the price from 10gb to 7gb, the first offer of 7gb will be accepted"

I hope this makes sense, I've never done a game development before so let me know if you have any other ideas or reasons why this wouldn't work :)