I'm sure every Sherlockian has a thing for this coat.
I personally have a huuuuuge thing for this coat. It is marvelous!
Now I know it still exists.
While I visit London I need to go there and no, not buy, just take a look at this magnificent coat.

Belstaff ‘Millford style’ coat.
Pure Irish wool tweed bonded with a sophisticated, ultra-light microporous film, to make it waterproof without altering the natural qualities of comfort and breathability.
£1,350 / $2,188 Available at Belstaff’s Conduit Street store in London.
Not available online.

BONUS FACTS: Belstaff originally discontinued the coat, but after the sucess of Sherlock and the amount of enquiries they had about it they bought it back into production and issued this press release on their website.
As with most of the clothing used in television shows, there are two back-ups of Sherlock’s coat in case one is damaged or lost during filming. That’s £4,050 worth of costume budget gone on just Sherlock’s coat.
The red button hole on the coat was added in by the costume department.