Basically buy records that you like.
There are some brilliant records out there, original & cheap.
Some are records that don't get played that much, but could still fill that dance floor.
It's not too long ago that I bought "The Incredibles" "Miss Treatment" from a Dealer for $40 (About £20 at that moment in time)
Purely because I liked it. That record would now cost much more to buy, Seen it recently around £100.
When paying good money, avoid the counterfeits, they are out there & we've all stories to tell.
However nowadays there is help at hand (Bootleg Guide is Essential) & by asking advice on this forum.
Best of luck, main thing is to enjoy.