The big bill from Customs and Excise is what would concern me. It might turn out not to be as cheap as you think and there might be warranty issues. If it breaks down or is faulty will Sony repair it here? I would check this out before going any further.
I bought a digital camera from the US and had to fork out £70 I think it was before I could get my parcel and thats a lot less than the cost would be for a laptop.