I didn't read all the posts, but after a short time it became apparent that the game developers have included code into the global market hq to create artificial scarcity. What I mean, if you need something, such as nails, they get a lower offering priority, or don't display at all. The reason for this is clearly to attempt to force people to use their credit card.
There are some things I would suggest that you change, such as advertising for needed items and allow user to post how much they are willing to give in return for said items. Or an auction type market. Either way, don't be so effn obvious about your money grubbing attempts and create a fair market place.
