Best of luck with your search Monty. I think the best of collection buying is likely gone although hopefully you do strike lucky. Some of my hits include
Mint collection of hardcore circa 300 including some £100+ tracks for £120 circa 2000
Rough condition but cleaned up well collection stored in garden shed with loads of white labels and doubles circa 500 records £50 2010
Rare genuine Italian collection circa 200 including Pink Mix offered £200 but guy wanted £100 only 2005 ish
Collection 50 88/89 mint slightly commercial house....free to a good home 1998
JJ Frost collection circa 2000 records £1000 bargain with loads of rare releases 2013
Deep US and UK garage 89 to 93 £60 for about 150 including some interesting bits 2012
Ex Surrey DJ collection, £100 for about 1300 records, gave loads away but few good bits 2008
Chicago collection, 100 records including some extremely rare releases £200 ish 2010
I have walked away from plenty of collections too. One was from a pressing plant rep, new white labels and promos of 92-93 hardcore. I wish I had bought the lot but did not have the money at the time so bought about 10 only. Some collections I have seen have been jokes, scrap or simply junk tracks fit for boot fair fodder.
My best hits were via dealers or ebay. Local papers died a number of years ago. Guy here in Aus goes to USA to buy his stock, does it twice a year and buys 1000's.
The Vinyl Junkie
S