You also have to consider what some people refer to dusty. Back when I started nobody cared if a Weller was stamped 00 on the bottom, if it wasn't Louisville, it wasn't desirable... I left Frankfort Centennials behind because the juice wasn't as good and I was finding better stuff. Had I known they'd become so desireable I would have stocked up on those too. And that leads to the "what should you hoard now" thread.
"everybody defamates from miles away
but face to face
they haven't got a thing to say"
I look for stores that have been around long enough to have dustys. If I'm fortunate the owner will be on premises and I'll ask him about any 'old stock'.
Finding dustys is more hunting than gathering but that's part of the fun.