Couple of old digs, come to mind. First would be Vinyl exchange, Camden town around 1987. The basement was full of singles, in the region of 10k most without sleeves, many 10-50p. Loads of Motown, tune up british x2, one way out British, nothing to good good for my baby, British, ECT. Bought loads of imports blind lots of c and w, a couple of bits that later turned out to be interesting. Good education for me.