Hello,
Not only would I have to purchase in the USA, from Europe (which might involve import duty, since we're talking about a box with a licence), it is also unclear if this will be accepted on top of the upgrade A/B pricing.
It's specifically an additional rebate for the Upgrade A/B pricing, so if you buy the Upgrade A or B for wherever you can get it cheapest in USA you can get the rebate from X-Rite specifically (but you can't pair it up with other X-Rite rebates like the trade-in deals for the new i1 Display Pro/Colormunki Display), at least that's how I read it - best to check carefully. The main restriction is shipping the upgrade inside USA/Canada, for this something like Shipito is your friend, or another mail forwarder like USABox.
Philip