I found the details for this company on the Allied-Pickfords website and phoned them for details.
They claim to be able to source certain makes of US cars at prices based on the factory invoice price. You order in the UK and the car is delivered via a franchised dealer in the USA.
They also claim to be able to get you finance based on the lowest available to a US resident taking your UK credit history into account, and motor insurance at low rates based again on your UK history.
There is a UK office but the deal is done via the sales office in New York.
Tomorrow the New York office will call to discuss exactly what is on offer and the cost. Before I explore this further I was wondering if anyone on VJ had heard of Autosource or had used them and could say if they are genuine or not.