Well, if I go, I go early, and before they let people in, casually ask the selling crew if they could direct me to where the gear will be located. Helps if it is in one place or you know where the items you want are first.
Certainly, when it comes to items to be savored or, more importantly to others, to be flipped for a big $$$ profit, then there's going to be competitive pressures, like gold nuggets strewn across a field waiting to be found. Then certainly people can and do become aggressive. If I've done my job at nicely communicating with the sellers, am way up in front, and advised them of what I'm looking for, many competitive disagreements have been resolved in my favor - partly because the other person is rude and nasty, and partly because most sellers would like to deal with "normal" and nice people.
Remember, the item still belongs to the sellers until they sell it, and they can, and sometimes do choose who to sell to. I get that for some people, it's an important means of adding to their livelihood, but that doesn't excuse rude behavior. In some cases, guys gather a whole hoard of stuff into one corner, then proceed to sort, check eBay, or otherwise figure out how to maximize their profit - in many cases they abandon stuff there and then. In a few nasty cases, they switch price tags, they hide additional stuff in other things, or they outright pocket items (like small camera lenses, tubes, tools, etc.). In short, some people steal at garage or estate sales.
Sort of reminds me of "the Treasure of Sierra Madre". So I understand why one would lose interest in going to advertised sales.
I didn't catch your name.) He said he was going to give it to his brother-in-law who is way into RTR's, so I think it is going to a loving home.