Not sure whether it is just me and my phone or more people encountered this, but when I place an offer in GE the keyboard which pops out sometimes instantly minimize.
That means instead of adjusting the price I end up confirming the offer (the button is right under the middle of keyboard).
Yesterday I managed to offer 120mil worth of supllies for 1gp each - if you find a problem with the keyboard please fix. (I managed to spam click and cancel the offer so no harm done there)