I moved my little one eyed icon up to the buy line and it did read "128" yet the 3rd place person, also on the buy line with a "128" got preference for the buy.
Each price value is actually a range of pixels on the screen and players can stop at any position in this range. You'll have to move to the top of the range to be sure to buy. When the dotted line turns solid you know you've gone far enough. The easiest way to be sure is to keep holding your UP button pressed until you hear the first ding.
I believe this is the same phenomenon that people use to block the bot from selling. The bot will run down and if someone meets him at the store line but doesn't buy bot will stay at the store price but won't sell to the store.
I noted this problem. I would guess it came when we switched to the new AI.