That has got to be one of the toughest questions in this hobby, and something I think about often.
I think I'm still trying to figure out an answer.
Certainly, I've benefitted often from this due to the incredible help from many JD'ers. At least when you buy them for other collectors, you know they're going to guys genuinely interested in them for their collection, and not for eBay.
If you didn't buy them, they could potentially be bought up by scalpers and sold for profit. So no harm done, in my eyes.
But maybe not. Perhaps, they would be purchased by collectors in your area. In that case, you would be hurting your local collecting community.
So...
I think that if you bought a couple of those figures because a couple of fellow JD'ers specifically requested them, then I don't think you're doing anything wrong. But if you buy every one of those rare figures off the shelf, not knowing if anyone here actually needed them... I don't know. Obviously, your heart is in the right place, but perhaps it would be more fair to leave them on the shelf, and just hope that they go to a good home.
Tough question, Brad. Definitely one of those "grey areas".