Can't buy a boxed version upgrade anymore ?

I’m trying to buy a boxed version upgrade of Nuendo 6 + NEK (from Nuendo 3) for a client. I want the box to be ready for when he will come to pick up his machine I’m going to build.
I want a box version and the store doesn’t offer this possibility anymore.
It is better for future reinstallation if it needs to be.

I commited him to buy all the Steinberg staff he was using (Virtual Guitarist, V Bassist, Groove Agent, the Grand, Nuendo etc…) and the boxes are his proof of loyalty and ownership. Don’t ask me why, but hardware guys need something in their hands when they spend money.

So, how can I get a box version upgrade ?