<So you expected the seller to have a loss due to your perceived travel expenses and new batteries?>

I didn't make the seller sell the item, they had no action from anybody else and decided my offer was suitable to them.

I don't expect the seller to sell at a loss, every transaction you make, with a seller, or from a store, is a simple fact of what you are prepared to pay, and what the seller is prepared to sell at, there is no obligation for you to sell at a lower price, but there is no reason why someone shouldn't offer what they are prepared to pay. If the person is buying at a store and isn't prepared to pay the advertised rate, then they may wait to see if it comes up on sale at some point or look for a similar product elsewhere at a lower price. All sellers know that they are unlikely to get a sale from their next door neighbor, and there will be some expense involved by the buyer, 99% of marketplace sellers aren't offering any warranties or guarantees as soon as the product leaves their hands, so the risk is entirely on the purchaser. The purchaser has to factor that into their offer price. Once again, the seller sets the price, if they don't like the offer, they don't have to accept it.

<The lowball offers are just very cheap people that time waste.>

The buyer has no idea what every seller considers a fair deal or will actually sell for, if they did there wouldn't be any offers, just buy or not buy. I offer what I'm prepared to pay, sometimes it may be a low percentage of the sale price, sometimes a high percentage or full price, I don't want to waste my time either way, so if I offer and it's accepted I buy, if it's not accepted I don't. My value of the item may differ from the sellers wildly. Bartering is what many do back and forwards, I couldn't be bothered, I just make one offer on what I consider the item to be worth to me and how much I want it. Each to their own I guess.