There are two ways to purchase a used item.

1. Pay the asking price. No awkwardness or boldness required; you're completely "nice", "going with the flow", low stress, etc.  Obviously the easiest route, but you also pay 100% of the asking price.

2. Haggle with the seller. This requires a bit of boldness, confidence, negotiating skill, mental effort, and in general: a bit of trouble. But you stand to gain a few $$$ by going this route, as the item will cost you less than it would have.

AND THEN THERE IS MY PET PEEVE:

3. Those who want "the best of both worlds" -- the convenience and ease of "single price" no-haggling like in #1, but with the lower price of #2. They ask ME to make an offer on my own product -- basically to haggle with myself. They expect me to jew myself down on their behalf.

When I list something for "$100 or best offer" that means I'm open to offers -- but you have to put yourself forward and make an offer. You have to risk a "no", risk offending me, etc. That's the price of any "discount" off my asking price.

I mean, if you're asking ME for a price, I already came up with one! It's called the asking price. I already think that price is fair, or I wouldn't be asking it. That's the only price I personally will give to a potential customer. If they want to haggle, THEY must haggle. That's their job. Or, they can always pay the asking price like 50% of people do.

I sold a fair amount on FB Marketplace and have gotten low-ballers. I've had a few people haggle in person but I say the price is firm. It does depend how desperate you want to sell something. Like I would look at how much it costs new, halve it, and maybe lower it. Or check similar listings. But if I'm desperate to sell it quickly, I'll price it lower. I also try to be more self-conscience about my spending. It's a pain to sell things on the used market especially with hyperinflation.