Generally, I don't have much use for retail outfits. There are a few who are wonderful assets to the hobby, but I've heard this same story from a few different people about this vendor. I believe they tried to swoop in on a deal I had made with a guy, but my seller also stood firm on his deal with me in the face of their phone calls to him, trying to persuade him to sell the game to them instead. Even when the seller had told them that I had rented a van and was on the way - driving the 100+ miles to get there, they said they could get there before me, and would give the seller an extra 50 bucks.

To me, that's not "business", that's sleazy. Good on the seller for sticking to our deal (which was really just my agreement to pay his full asking price).

In my case, it was the company mentioned in the OP actively trying to get a seller to break a deal we had - while I was on the road making a 100 mile trip.

That's not 'aggressive'. That's douchebaggery.

The seller told me there was never any chance of that happening. He said if someone did that to him, he would, and I quote "Punch them in the fucking nose.".

The old saying that applies here is "Don't shit where you eat.".

Roughly paraphrased.