Rule 4.1 refers to "total investment" and "total spent to purchase and prepare" which I'm inclined to interpret as not including shipping or import fees. Transporting the vehicle from one place to another isn't an inherent aspect of purchasing it, nor does transportation result in having more invested in the car (except perhaps emotionally). Transportation might count as an aspect of preparation, but that would be a pretty weak argument to make, since the cost of transporting a car to, for example, a cage builder, or even to the track, doesn't count.
When our team raced a British-market MG Metro we were asked nothing at all about any aspect of our budget, although it is true that in our case it was a previous owner who had imported it. I really don't think the judges would have cared even if we had been the ones who had brought it to the US, though. I suspect the same would be true if you were to bring over something unusual. We did, however, have to request a waiver for the "legal for US highway use at the time of their manufacture" part of the rules, which is something to keep in mind when looking at foreign-market vehicles.
1982 MG Metro 1300: IOE 2015 Pacific Northworst GP, Longest Distance 2010 Cd'L Box Wine Country Classic
1980 KV Mini 1: Worst of Show and Fright Pig Supremo 2009 Concours d'Lemons
1978 H Special: Second-Round Elimination 2010 Lemons Pinewood Derby at Sears Pointless
1967 SAAB 96: IOE 2012 Pacific Northworst GP