OK, looking at the breakdown most of the costs are similar to mine. My car is in Virginia so not far from Norfolk port. Ohio is quite a trek until you get to water (that's why I looked for an East Coast car, but in the scheme of things not that much extra). Your quote also includes road tax, reg fee etc which are all extra as doing this myself.
The duty is charged on the car, shipping and insurance. The VAT is charged on the total cost of the car, shipping, insurance and duty. Your duty and VAT figures may be a little low if my understanding is correct.
For the IVA side repeaters I don't think they will work in the reflectors on the front of a GS or Z06 due to the flared wheel arches. the manual states they must be visible from a minimum of 5 degrees from the rear of the car. I will check when it arrives as this may be a nice solution, but I don't think it will work for me.
If anyone has done this on a Z06 or GS please let me know.
I was going to mount black smoked LED's on the side vent area's behind the front wheel, as ultimately these items are cheaper to replace than drilling a front wing.
For the rear fog, I have found a company who manufacture LED rear reflectors based on the original GM reflector parts which can be used as additional brake lights. The manual states that for North American cars, if the fog does not have a Euro marking it can still pass if the intensity is correct so fingers crossed this will be a very neat finish. If not, hideous fog lamp at the back !
I was thinking about buying Euro wing mirrors with side repeaters in until I found out the price was £800 each.
Finally I used TransferWise to make the USD payment, they are much cheaper than banks, charge a fee but you get dollars at the spot rate not the banks buy and sell rate. This was a great plan only destroyed by the dealer who would not accept an "ACH" payment (this is the US equivalent of our BACS I have subsequently found out). They will only accept a wire transfer, so back to the bank I had to go. None of the cheaper transfer companies appear to use wire, they all use ACH. Apparently in the case of fraud an ACH payment can be returned for up to 60 days, by which time the car will be out of the country. This happened to the dealership 10 years ago with a Camaro and they lost the car and money. If you know someone in the US, use a transfer company to move the dollars to them and ask them to make the wire payment for you.