Warrany on camera bought in the US?

I'm thinking of buying the Nikon D800 but as it is £900 cheaper in the US (and I'm going to the us soon)
How does the manufacturer warranty work? Cover in the UK?
I have many friends who go to the us every other week so would getting a friend to take it there be possible if there was a problem?
Would It be best for me to get someone with an address there to buy it for me?

You will have to check with Nikon in the UK to see if they will honor a US warranty.

I know this. Nikon US will not look at, fix, allow you to install firmware from their website, or even sell parts to fix any camera not imported by Nikon US.

If you live in the US, you are best off buying a Nikon imported by Nikon US. If you buy a grey market camera in the US, you are on your own. But the cost is usually only $100 different at most for the US warranty cameras, so on a $3, 000 camera, it makes sense to pay the extra $100.

Check and see what restrictions - if any, that Nikon UK may have.

Be aware that when you buy it in the USA, upon returning to the UK you may be hit by import taxes.

The savings are largely illusory.

You need to pay VAT on the purchase price when you return to the UK, and it's the kind of thing which customs definitely look for on returning travellers. You'd then need to buy a separate repair warranty as the manufacturer's worldwide warranty is only valid for official imports sold through authorised distributors. You will also lose out completely on the considerable protection you get for up to six years from the purchase date under the UK Sale of Goods Act, and the resale value of grey imports is also lower.

If the camera goes wrong and you wish to return it for service under the US warranty then even if you do have associates regularly travelling across the pond, it will be slower and more awkward. If you manage to evade VAT then your couriers could be pulled up for it at a later date.

You have the facts, it's your choice. Note that although price haggling with UK retailers won't get much, if anything, off the cost of the camera, you can usually offset that considerably by haggling over the total package cost if you intend to buy additional lenses, flashguns, and especially accessories such as bags, cards, batteries, chargers, filters, tripods, or even an extended warranty.