I believe PMs have a report feature. If you get these, please report it, and I can check to see if it is a known scammer circumventing a ban. Also maybe reply to these telling them to post in your thread instead of using PMs.

EDIT: I'm not familiar with exchange rates and what not, and I know you're mostly dealing with large quantities, but you might be interested in my trade here if you are looking to increase your inventory. I imagine 1700 GCash is only worth pennies in USD for what you're spending, but at least it's something (and free, since you get LGG just for posting), and if all goes as planned, there will be a much greater pool of GCash available in the future.