for stuff i sample i tend not to buy stuff from the 80's-not really into the synths introduced around 78-79 ish, i love the organic feel of the 70's-best period in music pour moi.. 60's stuff is hard to find quality stuff to sample as far as the recording and the pressings, a lot of the stuff from the 70's is pressed, mixed, and mastered really nicely.. a lot of times i disregard anything that doesnt have a reallly cool cover or isnt from the 70's....
but as far as listening, i pick up anything from any period of time, mostly jazz, blue note, impulse, prestige, milestone, and fantasy..i try not to spend more than $25 on a single lp, unless its something i really want...