Able to purchase Explorer 40 in London

[MaineMan]

Wife happens to be in London and walked into a Rolex store. She asked if she was able to buy a 36mm Explorer for her husband's (me) 30th wedding anniversary and wanted it engraved on the back. They said they didn't have a 36, but did have a 40 available to purchase on the spot. Retail was 6,300 British Pounds. I told her not to get it because we had other things to purchase. My question really is, what would have been the price for the watch out the door? VAT of 20% and a 2% duty when declaring the watch? By doing some quick looking, I was estimating the watch to be $10,000+ USD by the time she left. Would have been nice though. She also didn't fabricate her story to purchase the watch.