come in the water's lovely.
I've always likened the record bars of all-nighters to a morrocan souk in reverse. you might like to offer the dealer in question a cup of tea, ask him questions about his family, if he has any attractive sisters, how much he earns from his daytime job (if applicable), if he lives in a flat or a house etc, etc, all this pleasant chit-chat can smooth the way for the moment when you go for the jugular, pitching in a ridiculous offer & waiting earnestly for his/her reaction. he or she could just as easily tell you to f**** off & then promptly warn other sellers that there's a nutter on the loose. it always worked with me though, being able to shave a pound or two off the asking price in the process.
seriously speaking, as others have said, get yourself on some mailing lists: pete smith, joe dunlop, rob messer, adey pierce, andy dyson are just a few that I'm signed up to. all offer great records at very fair prices. pat brady & john manship are also great sources, with soundclips, friendly communication & spot-on grading. I find these last two invaluable for searching out stuff previously unknown to me. finally, the financial committment required. my three credit cards are up to the hilt, but I just can't resist. online buying with ebay is also tremendously habit forming, watching the progress of auctions, the sniping, the buzz from winning stuff, the feedback scores etc, etc...
this happens to be my 3rd collecting cycle since I got into the music in the mid 70's & I'm enjoying it just as much as I did back then. good hunting!!
M