I ordered my 7th ed books through backerkit. When I asked why I didn't get a slip case with the books it was like "we don't have those left, tough luck kid!". So was this some extra special slip case at gen con this year?
Yes, we had to take down the slipcase version off Backerkit because they sold out. The slipcase editions come prepackaged from the printer in China that way, and we didn't have any more available at the time.
We don't have spare slipcases to sell right now either. But we could arrange to have some empty slipcases shipped from China next time we reprint.
Update: Slipcase Sets are back in stock and available again.