Its not lowballing its called offer up..

Level 5

You sometimes have to be firm if you don't want your items to be sold at a extremely low price. Many of my items are listed as firm and "not to ask me to lower the price or you'll be blocked from my page". I'm not that desperate to sell. I know the value of my items and I am already selling them less than market value. Being firm is what will weed out lowballers as well as the window shoppers, flakes, and other difficult people who like to waste your time. If you want to sell an item fast, then you should be descriptive on the ad that negotiations are welcome. A price should be aggreed upon before the meetup, not at the meet up.
Level 5

People like to test the sellers or people just don't read the item description at all. It's going to happen. If I list my item as "firm" and people message me a lower price or ask if it's negotiable, I simply block and report them. No apologies. Sometimes we have to take charge and not entertain these idiots (there are a lot of idiots on OfferUp who can't read and play so many childish games that it's sad). Just know your value, report the lowballers, and respond to the next serious buyer. If the person does not respect the terms of your ad, don't respond (just block and report).
Tags (1)
@XJeff083 I agree 100%
Level 4
Wow and thays why we all are allowed to have opinions....I have been doing this for several years and I know that when someone offers me 5 bucks on a item that is worth 100 they are not doing that because thats what its worth to them they are doing that because they are trying to get something for nothing and you are right they are playing a game but I refuse to play that game and I simply ignore them and dont let it bother me .
Level 3
Wow... hahaha, that was venting. Dully noted on the Market and Fair value thing. I just got one thing to add. As a seller, you don't know what someone is looking for. You can try to sell a pair of vintage socks not knowing what someone is searching for. Just because you as a (buyer) don't agree with the price, just maybe someone else will. People spend too much time worrying about other people rather than themselves. Blame that on society. Anyways, other than that, I agree with much of you are saying. But common, you can agree with me that we all look for the best deal we can get. Either by buying or selling. Some people have the ability to sell anything while others, well...not so lucky. Everything has it's value, rather it be Market, Fair, personal or by demand. Well... that's all I got.
Community Manager

Awesome post, @Jbalgas! Welcome to the community. These are some great reminders! 

Level 1
Waaa waaa want a shake with those French crys,. Survival by the rules of supply and demand if you can't supply it at that price someone else will. .. no hard feeling s it's just business. And don't forget that Walmart has overhead, and sell new merchandise, that comes with a return policy. So stop thinking your used items are worth the same. I LOVE THE BARTERING! !!! But I don't like people begging from me! There is a difference.., 3 no's from me then I get grumpy..m
Level 4
It really depend on the value of the item or if it’s new. Let’s say you are selling a brand new PS4 pro for $360, which retails everywhere for $400 plus tax, and the buyer offers $250- this is a low ball. The item is already cheaper than anywhere else in the world so offering 250 is ridiculous.
Negotiation means try me. Your low ball could define a buyer's high ball.
Level 4
Lowballs are annoying and a waste of time. Who list an item and then accepts an offer that’s 70 percent of the asking price? Nobody. Low ballers are like trolls.