Not actually sure if this is a thing already but it doesnt appear to be so...

In the trades section it would be awesome if all trades threads had to have a price, even if it were a rough guide price. I think it would make people more likely to buy, less likely to make insulting offers, or know what to offer, and just make things clearer all around

Of course haggling by pm, or however would still be fine but a rough price on trading thread i think would be a great addition