Even if anyone did, by the time your friend got there it could have been sold, or the dealer could have put his price up.
Meanwhile, 5 other stores that people say "no, don't have it", may get offered one the following day.
Plus, isn't part of the fun of collecting exploring all those nooks and crannies? I used to have a bunch of areas I'd go to in London - start at Notting Hill Gate with about 3 different places, then over to Camden Town, finally down to Tottenham Court Road for a couple in a side street ending with a trawl round Virgin, HMV and what was then Tower at Picadilly Circus.
Happy days...but if your friend isn't into all that and just wants a guaranteed success at a cheap price.....
..then he should try ebay and a little patience.