Everyone knows that the Record Exchange on Hampton is the first place to look for old vinyl LPs; few, though, ask to see the 45 room upstairs. Owner Gene Haffner keeps it locked, but ask and he'll prop open the door, hold the dimmer switch till the lights come on -- it used to be a film-screening room, back when the building housed a library -- and reveal aisles of 45's and EPs, 10,000 at last count (though the total collection, including those stored in Haffner's warehouses, exceeds 4 million). Need both the acoustic and band versions of "George Jackson" by Bob Dylan? You won't find it anywhere but on a 1971 Columbia single. The Record Exchange has it. Need a decade's worth of Bing Crosby Decca 45's, or perhaps an obscure Nick Lowe, Monkees or Atlantic R&N hit? They're all here, maybe even with a groovy picture sleeve.