camping out is fine. flipping is fine. buying things at low prices is fine. and they aren't taking advantage of the store by buying there.
And the thing is, is if that's their livelihood, and they need to fight like that... they are really in a low place.
I agree with all the above quoted remarks.
I have had that at a carboot sale as well - sometimes you get pushy shovy people but other times it can work well. We got rid of a fish tank. I mean, that's not easy to get rid of at a carboot sale, and it was a big one, but we did.
But yeah. I have seen more of the grabby behaviour at carboot sales than in stores. It's good to know it's not a normal practice.
Here if something isn't priced usually the person on the till makes up a price on the spot or negotiates it with the buyer. I have bought a bunch of G4 stuff lately that had no price, and they've been like, 50p? £1? It's all very casual.
Although I do wish that in this one particular (the best) charity shop, the heater wasn't blasting air at customers waiting to pay. That may be a deterrent method though from preventing long and protracted price negotiations xD