Time for an autoresponder.
"Sorry to have to resort to this but due to a large interest in a limited edition piece, we are unable to personally respond to inquiries regarding our GSG-16 in OD Green. To ensure we can keep moving forward and keep the process streamline across all of our products, we've had to limit our ability to respond to these inquiries. We will announce availability as soon as possible but for the time being, inquiries about their status will not be answered. Thanks for the understanding and have a great day."
Or something like that.