There was a time when there were loads of secondhand guitar/amp shops around East Anglia, although you don't seem to get them anymore. My brother-in-law picked up an Orange GRO100 from a backstreet dealer there about 15 years ago, which I promptly took off his hands for about £300 ( :twisted: ).
Maybe people are getting wise to selling desirable stuff through traditional outlets, choosing Ebay instead? I did see a nice Gibson SG in Trevor Durrants shop in Colchester the other week, that was £500.
Not sure where the "bargains" are these days. But then if I did I'd be completely broke, as opposed to relatively broke...