Sounds like a great idea - I would be very happy to see this happen and partake also.
I've only been in this hobby about 6 months, and have bugger all gear to be honest. Everything I have has been either bought, given, or bought VERY cheaply (read: nearly given) by this great crowd (IIS).
I was talking on the phone with Michael from Bintel a few months ago (very helpful I must comment). He mentioned the challenge of guessing the right qty of stock to order for each shipment. Things like a group buy would assist any retailer in getting "the container filled", which helps justify a shipment. Basically win/win.
I'd be interested to see how this develops - Count me in
Andy.