When scrolling through the trade office and you see an item that you would like but you think the price is far too high, there is a button next to the green tick button that says 'make offer'. You can click on this button and then make the seller an offer. Then on their sell screen there is another column that shows them a list of offers. Also you buyer could offer something other than what the seller is asking for. I.E, instead of coins maybe a building etc. They can then either accept it or decline it.
https://prnt.sc/igs4g2
This idea would save time trying to contact the seller and also the buyer would not need to place their own offer in TO unknowing if the seller has seen that offer. Plus it would save time if there are multiple trades being dealt with. Also if the time on the offer is nearly over the seller might want to accept the offer instead of not being able to sell at all. Just an idea, go easy on me