It would be worth getting definite confirmation of that from the seller. Although, good luck with that, as I've found Supermart's communication isn't their strong point.
I pick on this because a pal of mine in comics retail tells me there is 'no mechanism for getting around customs charges' when importing. He's frequently asked about importing anime by customers who think they can dodge charges by having it come through him.
Sadly, it seems like a lottery whether you get stuck with handling fees and VAT charges when you import materials. I've had sellers I used to use reliably for this sort of thing, only to be walloped with a little grey slip and a hefty charge out of the blue.
That said, I took delivery of the RightStuf! complete Nadesico collection last week, which came from Supermart and cost me about £25. I was SURE it would get flagged in customs, as my neighbours have had three (THREE!) grey slips between December and January. But, nope.
Worth having a bit of cash stowed away for such things just in case, I'd say.