HJ, what do you mean? Logged into by the owner, or by someone else? Cause if it's someone else, it can be abused (see my other posts on using it for quick uploads, then selling back the BW), and if it's the original owner, what if they accidentally upgrade the one they're on, but don't start anything with the extra hardware?
Yes it can be abused. But there are really people who accidentally purchased the wrong number hardware upgrades.
There should be limits like time delay (e.g. 1 hour before degrade task is complete) or huge AP cost (1000 AP per server) or you can only sell once per 7 days.