Hi David,
It all depends on several factors, is it from the west or east coast of America, is it going to be shipped in its own container or share a container with other items, how much will it weigh, what is the volume and is it by surface or air cargo? All of these have an effect on the cost. I cannot give you a rough price but to ship a car from the east coast it's about £2/3K from the west coast it's about £3.5/4.5k, by air it's a whole lot more. A car is not heavy in container terms, plus if you are in the uk you will have to consider import duty and vat. A good idea would be to contact the company and ask, they may have exported one of their kits before.
Regards, Cliff.